Lawfare Daily: Orin Kerr on the Digital Fourth Amendment

[Intro]

Orin Kerr: You see this across the Supreme Court's cases, cars, telephones, sense enhancing devices, GPS, sort of all these cases. I think you can really see a consistent method in the Supreme Court's cases of grappling with technological change by trying to maintain the role of the Fourth Amendment.

Jack Goldsmith: It's the Lawfare Podcast. I'm Jack Goldsmith from Harvard Law School, with Orin Kerr, a professor at Stanford Law School.

Orin Kerr: That's what equilibrium adjustment ends up being. It's sort of carrying out that instinct to try to find some middle ground in a world where the technology is constantly coming along and saying, oh, you have that old legal rule? Well, guess what? That legal rule that was balanced in the old world is now unbalanced in the new world. And it either dramatically expands government power or dramatically cuts back on government power. And now it stinks. What are you going to do?

Jack Goldsmith: Today we're talking about his new book, “The Digital Fourth Amendment: Privacy and Policing in Our Online World.”

[Main Podcast]

I think it's fair to say that you're the world's expert in this field, but you tell an interesting story, an interesting anecdote, in your introduction about how it almost didn't come to be, about your first job in the Justice Department and the kind of difficulties you faced in entering the field.

Orin Kerr: Yeah, well, first of all, thanks Jack, very much for having me on. The story of how I started in Fourth Amendment law and computer crime and digital evidence is I was hired by mistake. I showed up the first day of my new job at the Justice Department. I was so excited. I was gonna be a cybercrime prosecutor. It was the fall of 1998, early Internet boom.

And I showed up at the office and they said, so where are you going? And I said, I thought I'm going here. And they were like, ah, we were afraid of that. Yeah. It turned out they filled out the wrong form and they had wanted to interview me, but instead they hired me and they were stuck with me and they made absolutely clear they did not want to hire me.

And I ended up working on a lot of legal issues about computer crime because there was basically nothing else I could do. I was right out of a clerkship. I was 27 years old, and I knew nothing. And so they gave me all these legal projects because they figured, well, you know, at least the kid can do, can do law. And I ended up like, just absolutely loving these amazing legal issues that were just beginning to happen. And I've, I've kind of built a career on that since.

Jack Goldsmith: And what, you said you worked on, that they gave you a task that nobody else wanted, working on a manual for use by federal and state prosecutors on the law of digital evidence investigations. And in a way, that's what this book is about, right?

Orin Kerr: Yeah, that's exactly right. This is kind of, you know, many, many years later, a quarter century later. This is the legal issues that I first saw. And it was, it was, it was an amazing experience because I started off looking at these Fourth Amendment issues and some statutory questions, and they said, write a manual on how to investigate computer crime cases.

And I started looking at these old cases and thought, well, this doesn't really fit modern technology. This doesn't really quite work. How are courts going to figure this out? And I started seeing those legal issues and I knew I wanted, I was interested in becoming a law professor at some point and I, I switched directions.

I think originally I'd wanted to go into administrative law was my love of, legal love in law school. I thought that was going to be awesome. And instead I said, I, I, you know, I should start doing this because no one else is doing this and this looks like it's going to be big over time. So that's, I kind of switched directions and that's what I ended up working on.

Jack Goldsmith: Well, you've had quite a career working on it and this is a great book. The book is kind of in a way what you just described. It's about how the old Fourth Amendment doesn't really fit with new digital technology and what's to be done about it, how to work that out. Can we just start at the beginning and just remind listeners what the Fourth Amendment is, what it says, what it purports to do?

Orin Kerr: Yeah, so the Fourth Amendment: prohibition on unreasonable searches and seizures, enacted as part of the original amendments to the Constitution and ratified in 1791, and at the time there weren't police as we know them today. The authority was mostly about limiting the scope of warrants or orders that the king's officials could get to break into someone's house and look for evidence and, and that had to be limited in certain ways. That's what the 18th century focus was.

And then you start getting police in the 19th century, this whole idea of law enforcement, sort of a full-time police officer gathering evidence, making arrests and the like. And so the Supreme Court, starting really in the 20th century, starts looking at this 1791 language and saying, we kind of need to use that to craft the primary limits on policing.

So the modern role of the Fourth Amendment is it's what limits arrests. It's what limits breaking into someone's house. It's what limits stops and frisks. It's sort of, it's the main constitutional limit on policing in the United States today.

Jack Goldsmith: And as it was deployed in most of the 20th century, as you just described, it had to do with physical spaces. Can you explain the extent to which the Fourth Amendment kind of rested on an assumption about physicality?

Orin Kerr: Yeah, so in a world of physicality—think back to the 18th century or 19th century—the Fourth Amendment was really about physical space and what could be done in physical space, and the rules are very physically based. You know, government needs a search warrant to break into someone's house. Government does not need a search warrant to watch someone in public. That's, you know, sort of a very physical conception in figuring out how broadly a search can go.

How, you know, what's the scope of a search? The search unit might be like a, house, one physical house. The government can get a warrant to search a house for evidence. Can't get a warrant to search a city block for evidence. That's not a particular warrant. So just the rules of search and seizure naturally took on a physical aspect in a world where searches were unaided by technology. Just kind of physical searches by officers. Just naturally that evolved in the rules.

Jack Goldsmith: And then—and I'm just kind of marching through the early part of the book to set up the hard problems—and then the digital world descends on us. And so the whole book is about how to understand the Fourth Amendment and the doctrines that were designed, conceptualized in this physical world and how to apply them to the digital world, which is a whole, has a whole different set of conceptual assumptions.

So give us an overview of why the digital world is different and then we'll unpack how to think about it.

Orin Kerr: So the rules of search and seizure—the rule of sort of where can the government go to collect evidence and what evidence it can collect—is always going to be dependent on what's the technology of where the evidence is.

And so think about how a modern investigation might unfold where the key evidence in a case is information, you know, a text message somebody sent, for example, or something like that, or evidence of web surfing. Where's the evidence going to be located? Well, it could be on a digital physical digital device that has a ton of other information on it, and it's just stored as a digital record of past behavior, something which didn't exist as much in the physical world. You could have letters, of course, but most people wouldn't sort of put their every move into a letter in the 18th century.

And then, online. Think of so much of what we do, including recording this podcast is it's mediated by a digital network, it's something that's going to be stored by a server. It's a digital file somewhere. And so the government has to figure out who is behind the keyboard. Where is the file located? Who might have possession of that file?

The evidence has dramatically changed from the old physical world, where it's just kind of officer walking through physical space, looking at things, needing a warrant to break into a physical space. Now we're looking at just sort of data all around the world and how can the government get it and the techniques for getting it and the rules for getting it.

It's just that old physical assumption just doesn't - we can think about what's the modern version of that world, but we can't just simply apply the old rules to it because we, we end up with, in a lot of ways, kind of a Fourth Amendment free zone. Like if the rule - think of just sort of how you translate the legal rule into the technology.

If the rule is the government needs a warrant to break into a house, but the government can get all of its evidence without breaking into a house, well then, all of a sudden the Fourth Amendment doesn't mean very much anymore. It's just, you know, the government can do all the surveillance it used to without physical invasion.

And do you say, well, that's okay? Or do you instead embark on this task of kind of figuring out what's the modern-day equivalent of a physical invasion in order to restore the role of the legal protection in the new technological world?

Jack Goldsmith: Okay. And your theory for answering that question, the most important idea in the book, as far as I'm concerned, a hugely important idea is called equilibrium adjustment. And that's a mouthful. Can you explain in general, you just gave a little hint of it, how it works, what it means? Can you maybe use an example from one of the Supreme Court cases?

Orin Kerr: Yeah, so the basic idea is to maintain the role of the Fourth Amendment over time, not the rule, when those two diverge. And the idea is, really, it started off as just a description of what the Supreme Court has done with past technologies, ranging from the telephone, to cars, to lots of other examples.

The Fourth Amendment is kind of innately about technological change, because where the evidence is, is always going to be contingent on what the technology is used to carry that evidence and to store that evidence. And so the Supreme Court in the past—I looked back at old Supreme Court cases, this is going back to an article I wrote about a decade ago—it said sort of, how does the Supreme Court respond to new technology when this happens?

And I began to see there's actually a consistent method the Supreme Court has, which is as the technology changes and shifts how much power the government has to collect evidence, the Court seems to respond to technology by shifting the rule to restore the prior level of government power. And so an example of this—let me actually give an example that I start the book with—is cars.

In the 1920s, the role of technology, there was a dramatic shift in technology that had huge implications for the Fourth Amendment, which was suddenly everyone was driving a car. And they were carrying evidence in cars. And the problem that the courts had was that if you kept that old legal rule of having a warrant requirement, then suddenly that you could never actually investigate a car crime because people would just drive away before the warrant was obtained.

And the Supreme Court in a 1925 case called Carroll v. United States says, well, we're basically, we're dropping the warrant requirement for cars- what's known as the automobile exception in the United States. We still have it a hundred years later. And the idea is, well, just practically speaking, you can't investigate a case involving a car, evidence in a car, unless you shift the rule to a no-warrant rule, to just probable cause.

Responding to the technology, kind of trying to balance, sort of, basically the idea is to say, listen, technology has shifted the ground so much under the prior legal rule that we need to adjust the rule to restore the equilibrium and maintain the role of the Fourth Amendment over time. And so you see this so in some cases the Supreme Court loosens rules where the technology has made it harder to investigate and in other cases the Supreme Court strengthens legal rules or adds legal juice to the rule to increase legal protection in response to technological change.

And you see this across the Supreme Court's cases—cars, telephones, sense enhancing devices, GPS. Sort of all these cases think you can really see a consistent method in the Supreme Court's cases of grappling with technological change by trying to maintain the role of the Fourth Amendment, not the legal rule. And I, I give that the fancy title equilibrium adjustment because the thought is it's trying to, the Court is adjusting the rules to restore that prior equilibrium.

Jack Goldsmith: So I have to say, once you see the theory, you see it in every one of these cases. It's amazing how no matter what the doctrinal commitments of the justices and there are different ways of looking at what equilibrium adjustment means, but it's just on the surface of the cases, especially the digital cases as we'll get to, but even the old cases, it's quite remarkable.

Orin Kerr: Yeah. They, they all do it. Yeah, they all do it. As you say, independently of theoretical commitment. If you're an originalist, a non-originalist living constitutionalist, did they, they all have the same deeply, deeply felt need to do this except, and there is one interesting example, Justice Black turns out was not in favor of this method.

Everybody else across the board though, they all, they all do this and have, I think what makes it really interesting is, you know, this goes back a long, long ways. It goes back to the very early Fourth Amendment cases, and it's been consistent throughout.

Jack Goldsmith: So, I just want to press you a little bit on what's being adjusted to what. So the Fourth Amendment doctrine is changing, the Court is changing the doctrine of the Fourth Amendment rules in order to—and I'm just not sure which one of these things or all of these things it is-is it to preserve the purpose of the rule? Is it to preserve the role that the Fourth amendment was playing? And I don't know quite what that means.

Is it to, you also said it was, to kind of maintain the government's level of power? We don't want to give the government too much power to surveil, but we don't want to give them no power because law enforcement needs. What is being adjusted to what concretely? Maybe I don't know Katz. Is that an example that we can use to illustrate this?

Orin Kerr: Yeah, so there are lots of, lots of great examples and Katz is one of them. So let me just offer the big picture before we start looking at some examples. I think what's being adjusted is maintaining the role of the Fourth Amendment. I mean, think, think really, go back to real basics here. Imagine a world with no limits whatsoever on the police. The police can break into anyone's house at any time. They can arrest anyone at any time. Absolute, total police power. Zero privacy rules. We would all look at that and say, that's just absolutely horrible, right? That is a police state. That is dystopia.

Why? Well, too much government power is the power to abuse rules, abuse the authority—to, you know, the privacy rights of someone's house, arrest someone—it's all of these bad things that happen if there are zero legal limits. We can just, we can sort of think about why that is and come up with our economic answer for, you know, costs here and costs there. But really what's going on? Just a police state would be bad. I think that's the intuitive way of thinking about it.

And we can look on the other side to imagine a world where the police had no authority to investigate cases at all. They’re not allowed to break into someone's house at all. They're not allowed to arrest anyone at all. They, they just have zero ability to do any of these things. We also look at that and say, well, that's also a dystopia. You know, someone commits a murder and they say, I'm gonna kill someone again tomorrow. And the police say, gosh, we wish we could stop that person, but we can't. We have no authority to arrest. So we'll, we'll just let it happen. And that, that seems also really bad.

And so I think you've got sort of just, the nature of policing is there are these two extremes that are horrible and there's something—I'm not going to call it a sweet spot, it's maybe it's just sort of better than the rest—somewhere in the middle ground, enough power to enforce the law, but not too much power to abuse the law. There's some sort of instinct we have and people with different, you know, I don't know; a Bill Rehnquist is going to end up with one sense of what's perfect, and a Brennan is going to end up with another sense of what's perfect. But they're, they're each going to have some sense of somewhere in between those two radical extremes there’s a better world.

And I think that intuition is what's driving a lot of this. And it's kind of, you know, you can think of it as an optimization of some kind of overall public benefit, enough enforcement power, but not so much harm to civil liberties as kind of legal externalities on policing. You can think of it that way. But it's also just like, listen, those two extremes are horrible. Those are dystopian. Like that's, that's like bad movies and stuff we'd want to avoid.

So avoiding the horrible is really what's going on here. And that's why I think justices from all sorts of different ideological commitments, they can all realize when a rule is leading to outrageous results and they will think of it that way. They will just be like, okay, no, no, no, no, no, that's terrible. We don't want that. What we don't want. We don't want a world where either there are no limits at all on policing or there's just no ability to police.

And so they're naturally going to try to kind of look for some middle ground between those two. Enough limits on the police, not too much limits on the police – they’re all going to have that instinct. And that's what equilibrium adjustment ends up being. It's sort of carrying out that instinct to try to find some middle ground in a world where the technology is constantly coming along and saying, oh, you have that old legal rule? Well, guess what? That legal rule that was balanced in the old world is now unbalanced in the new ruled, and it either dramatically expands government power or dramatically cuts back on government power. And now it stinks. What are you gonna do?

And so they're all going to kind of look for that middle ground. They're all going to engage in this this method, and usually instinctively, they're not gonna be thinking about it as you know, they're not obviously like academics, their justices, practical sort of, they're gonna look for that middle ground. And they're gonna keep doing this across all these different technologies.

Jack Goldsmith: Okay, but there's, there's lots of room between those two poles and a lot of the argument in the book is about how to find the sweet spot, as you put it. Can you use Katz as an example to—and do you think, I think you think Katz was a proper equilibrium adjustment—to explain why the old physical world rules weren't working in light of new technology and why that was the right adjustment?

Orin Kerr: Great. Yeah. So in Katz the FBI is investigating someone who's a bookie. He's using a public pay phone to place bets for his clients. And the FBI tapes a microphone to the top of the public pay phone booth and records half of the call, the, the Katz’s side of the call whenever he's placing the bets. And the prior rule had been a search occurs when there's physical intrusion into a protected area.

And so the Ninth Circuit below says, well, there's no physical intrusion into a protected area here. This is merely a microphone taped to the top of a phone booth. And so there's no intrusion into anything. And it's, it's just a public pay phone. It's not like someone's house either. And so there's no physical intrusion.

And the Supreme Court says well, physical intrusion doesn't matter anymore. What really matters is, was it kind of a privacy invasion? And I think of it as being, they're basically asking, was it the modern-day equivalent of a physical intrusion? They're looking at the facts and they say, well, we're now in a world where people are having their most private conversations on phones. And in 1967, pay phones were a crucial way people did that. So listening in on someone's pay phone call is like an incredible privacy invasion.

And so they adjust - exactly what rule they adopt is a mystery. The opinion is kind of a hard opinion to parse. But they're expanding Fourth Amendment protections in the rule in order to maintain the role of the Fourth Amendment. You can't invade privacy like that, like listening in on someone's phone call because technology, that microphone had expanded government power under the prior legal rule.

Jack Goldsmith: Let's move more deeply into the digital and let's talk about the Carpenter case, which I think is the most important case in the digital world in the Fourth Amendment. I'm not sure if you agree with that, but I just think this case is so important. If you could just maybe give us the background in terms of the third-party doctrine, explain why the third party doctrine seemed problematic to some in Carpenter, how the Court resolved it.

And I don't think you talk about this much in the book, but I don't think because you had to work with the doctrine in the book, but I think originally in, in your scholarship, you weren't thrilled with Carpenter. I'm not sure if that's right, but why don't you just tell us about Carpenter?

Orin Kerr: Yeah, so Carpenter is the Supreme Court decision from 2018 saying that there are Fourth Amendment rights in cell site location records at least at scale. And so cell site location information, those are records that your cell phone provider is automatically creating about which cell sites your phone was connected to when it was on.

So whenever you turn on your cell phone, you know, you get, five bars or four bars or whatever it is. That's actually the strength of a connection between your phone and local towers, local cell sites that are connecting your call. And the idea is whenever you're connected to the network, you need to really connect to the network, and your phone is actually sort of seeking nearby sites in order to connect. And what that means is that the phone company is creating records of where you are by virtue of creating records of which cell site you were connected to.

And cell providers use this for, network reasons, not for law enforcement reasons. They just, they want to know where people are. They might say, hey, we need to add a new site over here because it turns out a lot of people are using our cell phone network over here or maybe less over there. And they, they use this for network reasons.

Well, it creates effectively tracking information about where people were in the past. If you assume people are next to their phones, which most people are, that cell site location information is going to effectively allow the government to roughly track where someone is in it. In the, in the Carpenter case, it was a guy involved in a string of robberies - ironically of cell phones. He was going into RadioShacks and the like and, and stealing cell phones with a group of co conspirators.

And the government helps to show this crime in part through cell site records. The records at the time were not very precise, so it's within a half mile to a mile and a half of the location. But still, that's pretty useful. The government shows, hey, look, whenever this store was robbed, all of these phones were in the area of the robbery. And, you know, the next day it was 50 miles away and they were all over there. And the next day was 100 miles there and they were all over there. And so the government relies on this.

And the Supreme Court says, you know, yeah, we used to have a rule—or we do have a rule traditionally—that if you disclose information to a third party, this is the so called third party doctrine, you don't have Fourth Amendment rights in what you disclose. So, I'm talking to you, Jack, on this podcast. If I tell you I robbed a bank yesterday, the government can go to you and say, did Kerr say anything about robbing a bank? And you say, yeah, he told me he robbed a bank.

And the thought is basically when I disclose to you, I've given up my rights and what I tell you, that information is now yours, it's no longer mine. And that has been applied in a couple of different network settings, most importantly, a case called Smith versus Maryland involving numbers dialed of a telephone. When I place a phone call—think 1980 technology—I dial the number and I'm telling the phone company, hey, can you connect me to this number?

And that's information. I'm basically telling the operator in a pre-computer world, please connect my call. That's records to them and they can disclose that. In that world, the content of the call is protected under the Fourth Amendment, but the government can go to the phone company and say what number did Kerr dial and get that information, because that's a record to the phone company.

And the government argued in Carpenter, well, this third-party doctrine applies, because after all, this is basically an information disclosed to the network for network purposes. You know, connect me basically over here, and that meant that there was no Fourth Amendment protection in the cell site records.

And the Supreme Court's answer is pure equilibrium adjustment. They say we have to say these records are protected because there has been a seismic shift in technological change. These records are unlike anything that has existed before. And if we don't say this is protected on the Fourth Amendment, then suddenly the government has this massive windfall of power that's been granted to them. They can engage in cell site, you know, tracking of everyone for years. And you kind of, we can't live in that world.

And they, the way the Chief Justice Roberts frames it is like the Fourth Amendment - he actually sort of uses this balancing framework. Fourth Amendment is trying to limit the power of the government, but not too much. And this, this shift has occurred and he's very much using this equilibrium adjustment type language.

And so the end result is kind of an exception to the third party doctrine, which everyone's still trying to figure out. We don't quite know what Carpenter means seven years later. But it's that and Riley versus California from 2014 are the two digital Fourth Amendment cases where I think the Court is taking these instincts and trying to craft a new kind of digital, digital specific Fourth Amendment.

And a lot of the book is basically saying, okay, these are the two examples the Supreme Court has gotten to already. What's the picture going to be or should be 20 years from now, 50 years from now, a hundred years from now? And in a lot of ways, the inspiration for me is I think back to the 1920s when the Supreme Court decides the Carroll case saying there's this automobile exception.

Somebody could have written an amazing book in the 1920s playing out how the automobile was changing Fourth Amendment rules and saying, here are all the rules. There’s got to be a kind of car specific automobile specific Fourth Amendment.

And that is, in fact, what we have. I'm teaching Fourth Amendment law today and very much it's this sort of technologically specific world of here are the car cases here, the home cases, and we just - we're going to need to add to that. Here are the computer cases.

We can already now kind of see what this world should be. And the point of the book is to play that out and start looking at a bunch of the big questions and see what this world that we're aiming towards should look like and will look like and think through it comprehensively now rather than just look at individual cases as they come up.

Jack Goldsmith: So you accept and try to theorize about, come up with a three part test for the Carpenter rule in the book, but do you think it got the equilibrium adjustment right? It does seem to me like, you know, at a, at one level, the fact that our phones are spewing off all this information all of the time, massively, massively empowers the government compared to the earlier baseline.

But I think you think it's more complicated than that in terms of equilibrium adjustment. So can you tell us whether you think that that was the time and the place and the right way to adjust the Fourth Amendment to deal with cell towers?

Orin Kerr: Yeah, so a key, key question behind this approach is you have to identify when has there been one of these seismic shifts? When has there been a moment where those old rules just really don't work anymore? And they've either given the government this huge windfall or they've done the opposite. They've dramatically lessened the government power to enforce the law.

And this is why I disagreed with Carpenter. I wrote an amicus brief in the case saying that we're just not in an adjustment point yet. And the reason why is that in the technology of 2018, when the case was being decided, the cell site records were not that precise. As I mentioned, it was sort of within a half mile to a mile and a half.

And once you once you say these cases are different, it's actually pretty hard to figure out exactly what are the cases that fall within that rule, sort of. You're creating an exception to a very clear rule. What's the exception? And that that can be done, but it's actually quite hard to figure out exactly where the carve out is. And I basically said this is not enough of a shift.

And what the Supreme Court said was, well, this case happens to involve half mile to a mile and a half kind of like not really precise surveillance. But we are confident that the technology has already shifted to being GPS like precision that it's going to be within 10 feet or 20 feet, and that this is tracking this extremely precise. And we think the technology is already there, given the five year old record. And we think it's that's where we are going to be.

And that's, so the Court takes that as the technological assumption that the nature of this tracking is extremely precise and then proceeds from there. They say, well, if we have this extremely precise tracking, what does that mean? And they, they come up with this rule. And if you accept the factual assumption then I think —I like Carpenter, I think it's right.

The problem is that even today, that technological assumption has not actually played out. And from what I can tell, cell site surveillance is still this kind of one mile kind of in the neighborhood, in the town, not on which city street or which room kind of stuff. So, so I, I think that the Supreme Court is maybe overly ambitious in thinking through what the technological shift would be.

So love the method, but think, yeah, probably the facts didn't support it in that one case.

Jack Goldsmith: And it makes me wonder what the proper unit of analysis is in figuring out equilibrium adjustment. Later in that chapter, you talk about some of the open questions about the third party doctrine in the digital world now that people are, that the courts are trying to sort out with regard to Carpenter.

Just to list those quickly: login addresses; IP addresses that we visit every time we, you know, click on something on the web; ride sharing records - when we take Ubers and Lyfts, we throw off data about where we're going; geofencing; and reverse keywords. And these are just five examples - I assume there are ten or fifteen or twenty more.

I guess my question is should the Court in doing Carpenter have been thinking about all of those cases as well in deciding when and how to do the equilibrium adjustment? What is the unit of analysis? It seems like a very hard problem to me because on the one hand, boy, thinking through the implications of Carpenter and all these other contexts is super hard, and you do a good job of it in the book. But, but on the other hand, if we don't adjust, in some sense, then the government is massively empowered.

So how do you think about that set of questions?

Orin Kerr: So I take the method in Carpenter and I, I look through the opinion and think through the concepts of how equilibrium adjustment could apply. And I basically say there's this three-part test that I think emerges from this, that fits the overall theme of the doctrine and fits what the Court was doing in Carpenter, and I play that out.

How does that apply to login IP addresses and how does that apply to web surfing? And some cases I think should lead to this adjustment and should be protected. Some shouldn't. Some I'm genuinely just like I'm not sure how that one should play out. A couple I think are just you could go either way.

And so I don't think the Supreme Court should have thought through those questions. And the Carpenter opinion is very expressly narrow in the sense the Court has this section where they say, like, we are not changing all these rules. We are not talking about this. We are just dealing with these facts and that, you know, that makes sense. They're narrow in that sense and let the lower courts work through all these variations. And lower courts have started to work through these variations.

One of the things that I think the Court maybe was not thinking about in Carpenter was that—it actually turns out that because of I think it's mostly because of limits on the scope of the exclusionary rule—it's actually quite hard to get a merits ruling on a novel Fourth Amendment issue, these days. There's so many ways out that lower courts have to avoid ruling on the merits. They'll say, well, this is a close call. The good faith exception to the exclusionary rule applies, we are not going to decide what the legal rule is. And so you just never get answers to a lot of incredibly important questions.

And what happened after Carpenter is, if you look back at sort of how, how the Fourth Amendment law, Fifth Amendment law developed in the 1950s, 60s, there were just an incredible number of cases that resolved a lot of doctrine pretty quickly. What we've had instead is Carpenter in 2018 and then relative radio silence. Supreme Court has not touched any of the stuff and lower courts because of the good faith exception have actually not addressed a lot of these things.

So there are a lot of really hard issues to tease out and I offer, you know, some answers in, in the book, for the direction courts might go. But the surprising thing actually is that we have not had this rush of cases seven years later to fill in what the answers might be under Carpenter, but in general, the courts at least have said, well, this is narrow, we're at least not going to establish lots of new rules here.

Jack Goldsmith: Although the Court can never control the impact of his precedence. It said that many times and in cases that turn out to have large implications. But can you just to make sure everybody understands explain briefly what the good faith exception is and why that takes care of a lot of the cases.

Orin Kerr: The good faith exception to the exclusionary rule is basically the rule that when there is a Fourth Amendment violation, suppression is not automatic - sort of, exclusion of the evidence is not automatic. And the Supreme Court in a series of cases starting in the 1980s expanded this exception. And really, I think the key case is 2011 Davis v. United States where the Supreme Court says there's no suppression remedy if the government relied on then existing appellate precedent.

And what does that mean? It means that if you are a criminal defendant or a lawyer for a criminal defendant, and the rule was against you, and you want to argue that the rule should be changed, you can make that argument. But even if you win at the U.S. Supreme Court, they say, congratulations, Carpenter, you have, you know, we're changing the rule, you get no benefit from that because the Court then says the exclusionary rule doesn't apply because the officers relied on then existing precedent.

What that means is that, first of all, if you're a lower court judge, you don't have to reach the merits of these novel issues. You don't have to reach the merits of these let's change the law kind of arguments. Even if you do, you don't have to give - no one gets relief. Actually, Carpenter doesn't get relief. No one actually - Riley doesn't get relief. No one actually gets out of jail. It all becomes, I think, kind of advisory opinions that that can be issued.

And the, unfortunately, the implication of this is that a lot of criminal defense attorneys will not raise novel Fourth Amendment arguments because they know it's not going to go anywhere. Even if they win, their client is not helped. And so it's just not on the, on the mind of a lot of defense lawyers.

Jack Goldsmith: It reminds me of qualified immunity, and the, where the Court will give immunity unless the law that was violated was clearly established, which the Court goes off on that ground — the lower courts often do — means the doctrine just can't develop because they never get to the actual merits they resolve it on. It wasn't clearly established enough, and this sounds similar to me. It sounds like a real structural hurdle to needed doctrinal development.

Orin Kerr: Yeah, and it's particularly painful for me because I have argued one U.S. Supreme Court case and it was Davis and I lost.

Jack Goldsmith: Oh, wow. I didn't know that.

Orin Kerr: Yeah, so I, I see it cited like every day and it just is like a, it's just painful every day.

Jack Goldsmith: So you lost the case and it keeps the Court from taking other cases in your field.

Orin Kerr: Pretty much.

Jack Goldsmith: Yep, okay, let's move on. So I just want to talk about a couple of other digital issues one that I'm particularly interested in is mosaic theory. Can you explain what that is? How it relates to equilibrium adjustment?

Orin Kerr: Yeah, so this is an idea that maybe Fourth Amendment protection should be about scale - that as soon as the government passed conducts a certain amount of surveillance, you get a search. And it goes back to the D.C. Circuit's opinion on the way to the U.S. Supreme Court in the Jones case. And that was the case involving 28 days of GPS tracking of a car.

And the D.C. Circuit said basically well, they put the GPS device on the guy's car. They start tracking him. That's not a search. But at some point by 28 days, a search has occurred because that tracking lets the government learn so much information about someone. You can really, if you know where someone goes over 28 days, wow, you've, you've learned a lot about them. It's sort of the equivalent that you might learn about them by going into their house. And therefore a search has at some point occurred.

And this gets to the U.S. Supreme Court, and there's no majority view for this theory, but there's some concurring opinions that endorsed it. And it's still in play today with lower courts dividing over whether there is an aggregation sort of limit on non-searches that become searches. Or to flip it, if something that's a search becomes a non search when it's done at a small scale. And so lower courts are just hopelessly divided on this question.

But I take that on because that's another really important question of if you accept that there's a at scale kind of special rule, you have to figure out, okay, well, what's the scale? And it leads to these endless line drawing questions about sort of how much is enough. How did the police ever know what they're doing is a search or not a search? Because they might not know when they, you know, press the button on the tool, how much information and what information is it going to collect. They might not know. And so it might be that there's a search depending on what the answer to that is, and they don't know that ahead of time.

And I, I come down pretty hard and arguing that this mosaic theory is just completely unworkable. There's just no lines that can really be consistently coherently drawn. And, and I think that the instinct I think is great. The instinct is basically saying technology allows the government to gather more information. That's what we're worried about - we're worried about the government having this extra power through technology, like GPS tracking over time.

The problem is that in, in equilibrium adjusting, if an adjustment is needed, you need to do so with a bright line rule that says, you know, this whole method has now a search rather than you can do a little bit., you just can't do a lot. It's that kind of middle ground that I think is unworkable. And I used to go through some examples of courts trying to draw these lines that I think have just been a total failure in saying why courts should reject this method.

Jack Goldsmith: So let me press you on the bright line rule requirement, which you and I both like bright line rules. But the counter argument is that just because you can't come up with a bright line rule doesn't mean you shouldn't try to lay down a principle and work it out over a set of cases, especially in a world where the government—you talk, I think it's in this context that you talk about artificial intelligence, maybe it was buying data—especially when there are tools where the government could potentially.

First of all, we're spewing off all this data all the time. Second of all, the government has tools that can increasingly harvest this data. I think to learn more and more powerful things about us, really intimate things about us, just based sometimes just on metadata. A critic would say the demand for rules is really putting a thumb on the scale for the government because, because during the period in which this government power is growing asymmetrically and we can't find clear rules, the government is just going to be a winner. And shouldn't we do something like maybe what Katz did and not being very clear or what Carpenter did and not being very clear and just indicate a shift of direction. So what's wrong with that argument?

Orin Kerr: So first, let me take on the idea that rejecting the mosaic theory is like a pro-government view. In a lot of circumstances, it's a pro individual view.

Jack Goldsmith: Explain that.

Orin Kerr: So where this plays out, you know, can the government use cell site location information to track someone for a few hours? Can they ping all the places that a particular phone was connected for, you know, a day, or how many phones were connected, a tower dump, they call it, a sort of how many phones were connected to that cell tower, or maybe they think there are two robberies, they want to know if they were connected.

So they'll say, let's get all the phones that were near the two towers at the times and near where those robberies occurred. And so if you're a mosaic theory fan, you say, is that a search? I don't know. Maybe, maybe not. Let's see what the government learned. And my answer would be, no, no, that's a search. They're all searches. Whenever you get cell site location information, categorically, that's a search. And so that's a situation where I end up much more civil libertarian than the mosaic theory adherents.

And I think what happened is—if I could just speculate—you know, the mosaic theory is introduced in Jones as a way of taking non searches and making them searches. Now it's taking searches and making them non searches. It's sort of, sort of political or ideological balance is going to shift or flip back and forth, depending on the context.

And I think the challenge is just the Supreme Court of Massachusetts, Supreme Judicial Court, has been the leading proponent of this theory. And what they have done in a series of cases is they look at the facts. And then they look at the information that was gathered. And then they say, okay, looking at it now, we say there was a search or looking at it now, we say there wasn't a search.

Now, interestingly, the Massachusetts Supreme Judicial court, if I understand their procedure, they actually can do a pretrial appeal to the state supreme court. So that allows them effectively to rule on motions to suppress before trial. Federal courts don't have that. And so what would happen in a federal court is you, the criminal defense attorney, file your motion to suppress, and then you can tell your client, listen, in five years, we'll get a ruling on whether there was a search here.

Well, that's, that's - the Constitution should be knowable to the police, not to justices looking at an appellate record years later. And so it, I think we're talking just about enough clarity to have some idea of what the Constitution allows the government to do is really - it's, it's not that high of a bar.

Jack Goldsmith: Okay, let's talk in terms of examples, finally, about buying data. I think the idea is that there's lots, you know, we give data away. Individuals give data away. Companies do things with that data, including selling that data that we give away. And the government can buy that data, they can purchase it. And they often do purchase it in the commercial marketplaces, I understand it, and all outside of the scope of the Fourth Amendment, and I think most statutory rules as well.

So the question is, is the, is the, is the mammoth production of data by individuals, the mammoth collection organization analysis of that data by companies, and then the mammoth selling to the government, which can use the data in theory without even worrying about the Fourth Amendment - is this an equilibrium adjustment situation?

Orin Kerr: And my answer is maybe someday, not now. Most, it's funny, most of the book ends up being pretty civil libertarian. Most of the time I'm, I'm arguing for adding Fourth Amendment juice to the system. And this is one area where I say, no, I don't think the case has been made, in part because the idea that this is a seismic shift has not been established yet.

There's a lot of concerns that this is going to be a seismic shift. But the evidence at least so far of the government buying Fourth Amendment protected data as kind of a way around Carpenter, a way around the Fourth Amendment rules - it's actually really, really hard to find examples of this happening.

And there's also responses by internet providers, by the providers themselves, by the companies to try to thwart this from happening. And so what seems to be going on? We're so early in the, this particular dynamic to tell. But what seems to be happening is when there's a story about the government trying to buy certain records of circumventing these privacy protections, there's a big public response. And part of that response is the internet provider saying we're going to block this.

So you have Apple adding privacy protections, not allowing apps to do certain things. You have Google ending their kind of holding of location records that people have opted into for geofence warrants. It turns out the privacy picture is not as bad as some people think, at least from the public record. That may change now, maybe in 10 years or 20 years, we look back on this and we're like, you know, hey, you said it wasn't so bad then it was sure is so bad now.

But at least right now we haven't had that factual predicate - that kind of like end of the world, not end of the world, but like, wow, dramatic shift in government power. A lot of fear of it happening, I haven't seen the evidence of it happening.

Jack Goldsmith: You are unusual, or at least on one end of the spectrum amongst legal scholars in your scholarship is cited a lot by judges. And you just said you filed amicus briefs, and you argued a case in the Supreme Court. And you talked in the introduction about, and you talked about having dialogue with judges about your, your scholarship. And this is all great in my opinion and extraordinary.

Can you talk about a couple of things? One, what are those conversations like? Are these like arguing about doctrine and two, how do you think about the relationship between your scholarship and what judges do?

Orin Kerr: So when I talk about kind of having conversations with judges, I just mean in public, through writing, through -

Jack Goldsmith: Yeah I know - I didn't, I didn't mean to suggest you're on the phone telling them how to decide cases. But you, but you are, you do seem, I mean they cite your scholarship, they argue with it. You're, you're dealing with, with doctrine, I think more than the average law professor. So what is that about?

Orin Kerr: So this is an area of law that judges really care about and they come to it without an obvious set of assumptions about what the answer should be way more often than in other areas. So, you know, a lot of, a lot of law professors, I think, don't engage with judges out of a sense that sort of the judges won't listen, the judges aren't interested. they've come up with their view of what the answer should be.

And a lot of it is, I think, a lot of law professors want to write in areas where judges already have pretty strongly held views. And so trying to persuade someone like, you know, you should be in favor of Roe v. Wade or something like that, like, guess what? They're going to have that conversation decades earlier and they're not going to change their mind because you cited some neat philosopher. That's just not how people think through hard legal issues.

But when it comes to this, it turns out, and I've just, I didn't, I wasn't really expecting this when I started writing in this area, but I was just delighted that it turns out a lot of judges say, well, this is, this seems important. I might decide a lot of cases and the one about new technology is gonna set a precedent. It's gonna matter and I want to get it right. It's just not obvious what the answers are.

And you could be a conservative, originalist, you could be you know, left of center, living constitutionalist - whatever your views are, they're actually all kind of coming to these issues with that same sense of like kind of history is looking at them. This is going to be one of their important opinions. They want to get it right.

And so they engage with scholarship a lot more than they would in other areas. I guess I think of it. It's like an amazing thing. and that judges are, they're acting in good faith, really trying to figure out what the answer should be way more than law professors usually give judges credit for. You know, we're pretty, it's a pretty cynical group among law professors.

So, so in a lot of ways my scholarship is directed to them, to that audience of the folks actually making the decisions - assuming they are actually thinking through it in, in good faith, which they really are. And that just, just like, okay, where's this going to land? And let's, let's think through this. And, you know, sometimes judges are not happy when you criticize something that they do.

But you know, by and large, it's - in a lot of ways, I think of it as a throwback to the 1950s, 1960s notion of, you know, academics following the courts, courts following, you know, that conversation happening. We've kind of left that model behind and, and, and I just think it's, there's a lot more to it that, that I think a lot of law professors could benefit from trying out.

Jack Goldsmith: You've written a lot of scholarship on these topics in law review articles and blog posts and things like that over the last quarter century, and now you've written a book. You've written a book that's kind of technology dependent. I mean, a lot of the arguments in the book are the state of technology circa early 2025. So I guess I'm wondering, and, and the book is also, it seems to me it's written for a little bit more general audience than your law review articles.

So I guess the question is why write a book now and how do you think about the problem of technological change in this area? I mean, are you going to have second and third editions every seven or eight years?

Orin Kerr: So I wrote the book because I had written a lot of individual articles over time, which were quite narrow. What I like to do when writing a law review article is write it on a discrete, doctrinal issue, kind of have it be, instead of it being, a lot, a lot of law professors write these grand theory articles, and like, everyone should rethink the way they think about law in 50 pages or something like that.

And what I like to do is have like a really narrow, like, here's an issue that's come up, you know, the scope of computer warrants. Or should you try to regulate how a search is executed in the warrant itself or something like that. Really discreet little issues. And I do that in part because, you know, I assume that judges, law clerks, litigants, like they have a legal issue and they can see that article and say, aha, that's actually really helpful for me and I can give my normative take in that. But that's it's designed to be kind of helpful to that audience.

And I thought, well, there's benefit to taking— instead of writing on all these little narrow issues and using the method in these narrow issues—of writing a one big picture book that says well here's the, here's the overall kind of big picture of what's going on and we're going to play that out.

So the first third of the book is like here's the method. And then the second middle part of the book is about here's what searches and seizures are in the standalone environment, here's what a search is, or here's what here's how the border search exception might apply, for example, to digital devices, which I argue it should not apply to digital devices. And then the last third is the network problems.

And so the thought is, if you have just one book that sort of gives the whole big picture that really can give people an idea of the big direction, the big shift that's occurring in a way that you're not going to get from just these individual discreet articles.

I mean in terms of whether it's gonna be outdated. You know, I think a lot of these issues have been around for a long time, surprisingly. We talk about technology changing really rapidly in a lot of ways, we're talking about new issues come up, but the old issues don't go away in a way that we might expect.

So, you know, the Supreme Court's never decided a case on Fourth Amendment rights in email. Email's been around for a really, really long time. And so the technology is evolving, but a lot of the big questions are around, and they're going to stay around for, I think, decades to come.

Jack Goldsmith: Sure they will. My last question is, so I thought you were very successful in going up a few thousand feet in this book compared to your articles, and in kind of laying out in one place what the Fourth Amendment is, how it normally works, here's the basic doctrine, here's the equilibrium adjustment theory, and here are a whole bunch of applications in the digital realm.

I find that when I have written books that do something like that, that try to take other things I've written and kind of stitch them together in some sense, add some parts and weave it all together, I find that I had to rethink things sometimes, or I learned something new. And you also dealt with some new issues in this book.

I'm wondering if there was anything in the process that sticks out as that you realize that you didn't realize before, or that you had some insight in the course of putting this together, or some adjustment to your way of thinking about things?

Orin Kerr: So in writing the book I made a point of not going back and rereading the articles. So I wanted it to all fit together my kind of current thinking rather than here's what I said in 2005 and here's what I said in 2010. And so there were changes, there are ways in which the arguments end up coming out a little bit differently, absolutely.

So I have a chapter on the rules for search warrants and digital warrants and how to limit the scope of a digital warrant. And I end up in the same basic place of this. You know, I wrote an article on this in 2005 and another 2015, but the argument I think now is a lot tighter and it fits together with other arguments a lot better than it was in those earlier efforts. So, and I think I have a line in there to the effect of like, hopefully these are improvements on the prior, the prior views.

But yeah, I made a point of, of not going back and just trying to, trying to give the whole picture today without reference to all those old bloggers.

Jack Goldsmith: Well, it's very successful. Congratulations, Orin.

Orin Kerr: Thanks so much, Jack.

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