Where a defendant is barred from raising an issue on direct appeal due to a failure to object at trial, he may not pursue the same claim in a petition for writ of habeas corpus unless the claim depends substantially on facts that the defendant did not know and could not reasonably have known at the time of trial. The defendant here argued that whether a claim can be raised in a habeas corpus proceeding depends on the nature of the claim, not on whether it was raised at trial. The Supreme Court rejected this argument, noting that defendants approach would circumvent the main purpose of the forfeiture rule, which is to encourage prompt correction of trial errors and thus avoid unnecessary retrials. The Court acknowledged that a defendant may still have recourse on habeas review if counsels failure to object fell below an objective standard of reasonableness, or if the claim depends substantially on facts that defendant did not know and could not reasonably have known at the time of trial. The Court cautioned, however, that the latter exception did not entitle a defendant to avoid the procedural bar by relying on facts that add nothing of substance to what the defense knew at the time of trial.