Another interesting case taken by the Supreme Court, Davis v. United States. The scotusblog page is here.
The facts of the case are not too complicated. The defendant was a passenger during a routine traffic stop. When the driver failed field sobriety tests, the police asked the defendant to step out of the car. The police later determined that the defendant had provided a false name, and arrested him for that offense. The [police then searched the vehicle, and found a gun in the defendant's jacket pocket.
The problem is that this case occurred during a significant change in the law by the Supreme Court. Under the old law – as expressed in Belton – the search of the jacket pocket was not a Fourth Amendment violation. However, in 2009 in Arizona v Gant the Supreme Court changed the law about automobile searches. In that case, the Court held that police officers may search the passenger compartment of a vehicle incident to a recent occupant's arrest only if it is reasonable to believe that the arrestee might access the vehicle at the time of the search or that the vehicle contains evidence of the offense of arrest.
In other words, the search was permissible under the existing Supreme Court precedents, but now appears to be unconstitutional.
The question presented in the petition for cert. was: "Whether the good-faith exception to the exclusionary rule applies to a search authorized by precedent at the time of the search that is subsequently ruled unconstitutional." In plain English, this means: should the court throw out the evidence even though the police acted in accordance with the Supreme Court cases in effect at the time?
My initial guess is that the defendant has an uphill battle here. The purpose usually cited behind excluding evidence from a trial for constitutional violations is to deter wrongful police actions. In this case, the police acted in a reasonable belief – based on the existing Supreme Court cases – that their conduct did not violate the Fourth Amendment. So nothing would be gained by excluding the evidence from the defendant's trial in this case.