https://www.techdirt.com/articles/20190729/14374142672/district-court-rolls-back-magistrates-decision-says-compelled-fingerprint-product-isnt-fifth-amendment-issue.shtml

So much for the Fifth Amendment. At least in Idaho, anyway. Back in January, a magistrate judge rejected the government's attempt to force a suspect to unlock a seized phone using his fingerprints. The judge found the government's request to be a violation of two rights -- the Fifth Amendment protection against compelling a defendant to testify against themselves -- and the Fourth Amendment, since the government hadn't shown a connection between the accused and the seized device.

As the magistrate pointed out, the government could not rely on "foregone conclusion" arguments because it had failed to develop any foregone conclusions. The warrant itself said the government was seeking to search the phone for "indicia of ownership" -- something the government should have been able to plausibly allege long before it started asking the court to compel the suspect to unlock the device.