To demonstrate cause for a procedural default, a petitioner must show that "some objective factor external to the defense impeded counsel's efforts to comply with the State's procedural rule."

A fundamental miscarriage of justice of occurs "where a constitutional violation has probably resulted in the conviction of one who is actually innocent."

A claim of ineffective assistance of counsel constitutes "cause" if it is the actual cause of a procedural default.

"Cause may be demonstrated with `a showing that the factual or legal basis for a claim was not reasonably available to counsel,... or that "some interference by state officials" made compliance impracticable,...[or that] the procedural default is the result of ineffective assistance of counsel.'"Id

In all cases in which a state prisoner has defaulted his federal claims in state court pursuant to an independent and adequate state procedural rule, federal habeas review of the claims is barred unless the prisoner can demonstrate cause for the default and actual prejudice as a result of the alleged violation of federal law, or demonstrate that failure to consider the claims …

To demonstrate prejudice, the petitioner must show "not merely that the errors at his trial created a possibility of prejudice, but that they worked to his actual and substantial disadvantage, infecting his entire trial with error of constitutional dimensions."

If a claim is procedurally defaulted, the court may require the petitioner to demonstrate cause for the procedural default and actual prejudice from the alleged constitutional violation.