The US Constitution's Fifth Amendment protection against self-incrimination does not prohibit police officers from forcing a suspect to unlock a phone with a thumbprint scan, a federal appeals court ruled yesterday. The ruling does not apply to all cases in which biometrics are used to unlock an electronic device but is a significant decision in an unsettled area of the law. The US Court of Appeals for the 9th Circuit had to grapple with the question of "whether the compelled use of Payne's thum...