US v. Davis: In 2000, Davis was shot and treated at a Maryland hospital. As part of the investigation of his shooting, police seized Davis's bloody clothes from underneath the bed on which Davis lay in the emergency room. Nothing came of that investigation. However, in 2004, a neighboring police agency was conducting an investigation of a murder in which Davis was a suspect. They took the bloody clothes (which had been retained in the other agency's evidence room all those years) and used them to procure a DNA sample which could be tested against evidence from the murder scene. It was not a match, but the resulting profile remained in the database where, later in 2004, it was used to link Davis to a botched armored car robbery. As a result of the match, Davis was charged with various federal offenses arising from the robbery. After the district court denied Davis's motion to suppress the DNA information, a jury convicted Davis.
On appeal, the Fourth Circuit affirmed Davis's convictions. The court focused primarily on questions dealing with the DNA evidence and its collection in light of Fourth Amendment protections. First, it concluded that the initial seizure of Davis's bloody clothes was proper under the plain view exception to the warrant requirement. Second, it concluded that the initial search of the clothes to procure a DNA profile violated the Fourth Amendment and assumed (without deciding) that the later use of the DNA profile to link Davis to the armored car robbery was also a violation. However, suppression of the resulting evidence was not required under the ever expanding "good faith" exception set forth in recent Supreme Court decisions like Herring and Davis. The court also concluded that the district court did not abuse its discretion by prohibiting a defense expert witness from testifying about problems with the procedure police used during a lineup in which Davis was identified by an eyewitness.
Judge Davis dissented, disagreeing with the majority on both the plain view analysis and the conclusion that the exclusionary rule should not apply.
Orin Kerr at The Volokh Conspiracy has some additional thoughts.