[JURIST] The US Supreme Court [official website; JURIST news archive] on Wednesday ruled [opinion, PDF] unanimously in Walker v. Martin [Cornell LII backgrounder; JURIST report] that a state law barring a prisoner from collaterally attacking his conviction is adequate to support a procedural bar to filing a habeas corpus petition. The decision upholds a California state law preventing prisoners from collaterally attacking their judgment when the prisoner "substantially delayed" filing his habeas petition. Writing the opinion for the court, Justice…