A federal appeals court on Tuesday heard two cases about warrantless tracking, a procedure fraught with uncertainty in the wake of a 2012 U.S. Supreme Court ruling that held such GPS uses are Fourth Amendment searches.

U.S. Court of Appeals for the First Circuit Chief Judge Sandra Lynch, with senior judges Kermit Lipez and Norman Stahl, heard arguments in the two unrelated cases, U.S. v. Báez and U.S. v. Oladosu.