Freedom to Tinker reports that the U.S. Court of Appeals for the Sixth Circuit has ruled that email is protected by the Fourth Amendment. The Fourth Amendment requires a search warrant issued by a judge before law enforcement officials can search premises, and has long been applied to opening sealed paper mail. But some law enforcement officials have wanted to simply get service providers to supply them with the contents of a customer's email without a warrant, on the rather thin basis that the emails are stored in a readable format. The ruling is significant and ensures that citizens are protected against frivolous or unjustified searches of electronic mail.