Today the Supreme Court hears oral argument in Pearson v. Callahan. The underlying Fourth Amendment issues are nicely explained in Sherry Colb's most recent FindLaw column. There is, in addition, a procedural issue that may prevent the Court from reaching the merits: whether to overrule Saucier v. Katz, a question that the Court specifically added to the petitioners' questions. In Saucier the Court held that when deciding a civil case in which the defendant raises a qualified immunity defense, the courts should first decide whether the plaintiff's claim states a constitutional violation, and if so, only then consider whether the defendant had qualified immunity, i.e., whether at the time of the alleged rights violation it was clear that what the defendant did violated the plaintiff's rights. The Saucier rule has been justified on the ground that without it the law could become frozen, with courts only ever deciding what the law was, rather than what it is. It has been criticized, however, on the ground that it is too rigid, and that therefore when courts are presented with an easy qualified immunity question and a hard merits question, they should be permitted simply to decide the qualified immunity question.
If the Court chooses not to overrule Saucier, or if it does overrule Saucier but decides that this is the sort of case in which it will exercise its discretion to decide the merits first anyway, then the Fourth Amendment issues discussed in Sherry's column will be decided. In particular, the Court will have to consider whether an undercover informant can give consent to a warrantless search on behalf of the target of a police investigation, where the target himself does not consent. As she explains, there are good reasons to think the answer should be no---that the rationales for permitting undercover informants and consent searches don't mix.
I want to add that the underlying constitutional law (per United States v. White) in this area is simply terrible. Indeed, it is downright unAmerican. That underlying law permits the police to hire a confidential informant to befriend anyone, without any requirement that there be probable cause, or even reasonable suspicion of criminal activity by the target of the investigation. In other words, as far as the Constitution as interpreted by the Supreme Court is concerned, the police can act pretty much like Stasi of the old East Germany. (For the film version, see The Lives of Others.)
Undercover agents may well be vital to legitimate police investigations, but that does not mean that police should be able to employ them without grounds for suspicion that are presented to a neutral magistrate. Matters might be somewhat different for sting operations and so-called "reverse-sting" operations, e.g., for cases in which an undercover police officer poses as a drug buyer or drug seller to ensnare someone who self-selects for criminal activity. But where the police designate someone to infiltrate a target's business, home, and life, surely something more than a hunch (or a vendetta) ought to be required for singling out that target.
The Supreme Court is highly unlikely to reconsider the constitutional doctrine that permits the use of undercover agents without probable cause or a warrant, but Congress could and should provide statutory protection, ideally in a non-election year.
Posted by Mike Dorf