[JURIST] The US Supreme Court [official website; JURIST news archive] on Monday unanimously ruled [opinion, PDF] that lower federal courts may not issue writs of habeas corpus to state prisoners unless their confinement violates federal law. The court overturned a ruling by the US Court of Appeals for the Seventh Circuit [official website] in Wilson v. Corcoran [docket], which granted habeas relief [opinion, PDF] to Joseph Corcoran, convicted of killing four men and sentenced to the death penalty. The court…