A federal court has issued a search warrant compelling a Los Angeles resident to unlock her iPhone using Touch ID so that the FBI can gather evidence from it. While courts have issued similar orders before, this is the first time it has happened in a federal case, and a rare example of such a warrant being issued.
From the Los Angeles Times:
There, authorities obtained a search warrant compelling the girlfriend of an alleged Armenian gang member to press her finger against an iPhone that had been seized from a Glendale home. The phone contained Apple's fingerprint identification system for unlocking, and prosecutors wanted access to the data inside it.
The U.S. Supreme Court has previously held that a warrant may compel someone to unlock their phone with their fingerprint, as a fingerprint is thought to be physical evidence, which a person in custody may be required to provide. However, one case held that a password cannot be compelled because disclosing it could be tantamount to testifying against oneself, a possible violation of the 5th Amendment right against self-incrimination.
Some groups have also argued that compelling someone to unlock a phone with their fingerprint is also a 5th Amendment violation, but debate still continues on the merits of that particular argument.