Can the UK Rescind Its Withdrawal from the EU?

Events in Washington may overshadow what's happening around the world, but nobody can miss the confusion that attends the British government right now. Two ministers have resigned over Brexit, and the furture of Britain’s negotiations with the European Union is radically uncertain. All of which led me to an odd musing—what if Britain changed its mind? Not that it is terribly likely to happen, but what would be the result if the U.K. decided it wanted to stay in the EU? As a formal matter, it has submitted notice of its intent to withdraw under Article 50 of the treaty that created the European Union. Can the U.K. unilaterally withdraw its notice and just ... stay? Or if it sought to withdraw its notice, would it require the agreement of the EU? Of if the EU must concur, would it be the European Commission who would have to agree, the European Parliament, or, as I suspect is the case, the goverments of the other 27 remaining EU member-states?

As I said, the hypothetical is still unlikely to occur, and no doubt the formal legal answer to these questions is “it’s unclear.” But I was curious enough to ask a friend who works for the European Commission, and he was kind enough to send along the two references:

• EU Parliament study: “The (ir)-revvocability of the withdawal notification under Article 50 TEU”
• EU law analysis: “Can an Article 50 notice of withdrawal from the EU be unilaterally revoked?”

Both say that the legal question is open, but provide enough analysis that they seemed worth sharing.