The Supreme Court has ruled by 5-4 split decision that the exclusionary rule, which bars evidence obtained in an illegal search, is not absolute. The case in question, Herring v. U.S., involved a police officer, Mark Anderson, who executed a warrant to arrest Bennie Dean Herring, (described by the Times as "very unlucky as well as felonious in his conduct,") who had previous run-ins with the law and was at the Sherriff's department to retrieve items from his impounded car. A search turned up a gun and metamphatamines in Herring's possession.
The warrant had actually expired several months earlier, so the search was illegal even though Anderson had made an honest mistake. Evidence illegally obtained is usually inadmissible. But with the court's decision, under circumstances such as the one above, this won't be the case.
The problem is that Roberts' opinion, which, according to the Times, finds that "police mistakes leading to an unlawful search are the result of isolated negligence attenuated from the search, rather than systemic error or reckless disregard of constitutional requirements, the exclusionary rule does not apply," which has a much broader potential effect than simply negligent recordkeeping. It could end up putting the burden of proof on the defendant's lawyers to prove the officer acted recklessly, rather than simply made a mistake. But we have the exclusionary rule for a reason, and this ruling would seem to invite abuse from police officers who want to perform a search but don't have probable cause. Over at SCOTUSBlog, Tom Goldstein, who was part of Herrings' defense team, explains better than I can and in much more detail.
-- A. Serwer