The following commentary is cross-posted on The Volokh Conspiracy.

Have you heard of the "14-Day Clause" of the Constitution? If not, you should take a look at the Supreme Court's opinion yesterday in Maryland v. Shatzer. Shatzer is an intriguing example of how the Supreme Court makes rules in the area of criminal procedure. It's particularly notable in that it introduces a very rare (but not unprecedented) numerical rule to implement constitutional protections.

Shatzer is a case on the law of police interrogations when a suspect is in police custody. It's one of the dozens of spinoff decisions from the 1966 blockbuster Miranda v. Arizona, also known as the "you have a right to remain silent" case. The specific question in Shatzer is whether a detained criminal suspect who has asked to speak with a lawyer can ever be questioned again without a lawyer present. In a 1981 case, Edwards v. Arizona, the Supreme Court held that when a detained suspect asks to speak with a lawyer, the police cannot try to persuade him to change his mind. They have to stop the questioning, and they cannot restart the questioning, even after time passes and the suspect has met with his attorney, unless the suspect reinitiates the questioning on his own.

The issue in Shatzer was whether that rule continues to apply if the suspect has been released from police custody and is then rearrested. In particular, do the police have to honor the earlier request for a lawyer? The Miranda protections don't apply when a suspect is no longer in custody. When the suspect is arrested again, however, he regains his Miranda rights. The question is, does the break in custody reset the clock on the effect of the suspect's earlier request to speak with a lawyer? Or does the fact that the suspect is released from custody make no difference at all, such that the police are forever barred from approaching the suspect without a lawyer whenever he is in custody?

Two practical points make answering this question unusually hard. Point One is that the police need clear rules that answer the question with certainty. It doesn't work to give the police complex legal tests to apply on the fly: They need clear rules to know what they can and cannot do. Point Two is that the two obvious candidates for clear rules each create absurd results. If you say that any break in custody, however short, resets the clock, then the protections are meaningless. If a suspect asks to speak to an attorney, the police will just "release" the suspect for 30 seconds, re-arrest him, and then restart the interrogation. That doesn't work. On the other hand, if you say that the break in custody has no effect at all, then all sorts of strange consequences follow. A request to speak with an attorney in one case will inoculate the suspect from police interrogations for the rest of his life for all of his unrelated crimes. A request to speak to an attorney at the age of 18 in one case would bar questioning a half-century later for something entirely different. That doesn't work, either.

So what to do? What clear rule on how long the break must be to reset the clock is workable here? Enter the 14-day rule, announced today in Shatzer in a majority opinion by Justice Scalia:

We think it appropriate to specify a period of time [at which time the clock is reset]. It seems to us that period is 14 days. That provides plenty of time for the suspect to get reacclimated to his normal life, to consult with friends and counsel, and to shake off any residual coercive effects of his prior custody.

The 14-day limitation meets Shatzer's concern that a break-in-custody rule lends itself to police abuse. He envisions that once a suspect invokes his Miranda right to counsel, the police will release the suspect briefly (to end the Edwards presumption) and then promptly bring him back into custody for reinterrogation. But once the suspect has been out of custody long enough (14 days) to eliminate its coercive effect, there will be nothing to gain by such gamesmanship"”nothing, that is, except the entirely appropriate gain of being able to interrogate a suspect who has made a valid waiver of his Miranda rights.

As a matter of policy, I think that's a pretty good rule. But why precisely 14 days? That is, 336 hours, or exactly 20,160 minutes? There is no 14-day Clause in the Constitution. (I checked.) Why not 15 days? Or 13.491 days?

As far as I can guess, the only reason 14 days was chosen is that it's easy to remember and seemed in the right ballpark. Jews started measuring seven days as a time period in the 6th Century BC; the Romans then adopted it, measuring time in 7-day weeks; and two-thousand-odd years later, on February 24, 2010, a majority of the Justices on the Supreme Court thought that one of those was too short, three was too long, and two seemed about right. And how did the Justices know that 14 days would be about right? Based on their extensive experience being arrested, perhaps? Presumably not. But no matter. Fourteen days seemed about right, and so the 14-day rule became the law.

If you're wondering how Justice Scalia could end up writing an opinion that sounds so legislative "” picking 14 days out of thin air "” you need to know Justice Scalia's history with Miranda. Justice Scalia intensely dislikes the entire line of Miranda cases. The Court has sometimes referred to the Miranda rules as "prophylactic." That is, they are rules created to protect the Constitution, and enforced as constitutional law, but not necessarily constitutional rules themselves. In his dissent in Dickerson v. United States, Justice Scalia argued that this entire approach was illegitimate. He would overthrow the entire line of cases as an illegitimate power grab.

It's not clear how many Justices continue to see Miranda as just "prophylactic" after Dickerson. But Justice Scalia still does. And he has long had a special dislike for the Edwards rule in particular. (Remember, that's the rule that the police have to stop interviewing someone, and can't restart questioning, if he asks for a lawyer.) In a 1990 dissent, Scalia described the Edwards line of cases as "prophylaxis built upon prophylaxis, producing a veritable fairyland castle of imagined constitutional restriction upon law enforcement."

But if you can't beat "em, join "em. Or at least join "em if that means you get to write the opinion that substantially limits the effect of the Edwards rule. And if you're going to write an opinion that you see as merely "prophylactic," presumably you're not bound by your usual approach to constitutional interpretation. With apologies to Chief Justice Marshall, it is not a Constitution you are expounding. So explicitly policy-based rulemaking becomes more understandable, even if it's jarring coming from Justice Scalia.

Posted in Maryland v. Shatzer, Analysis, Merits Cases