What is the test for an abuse-of-the-writ claim in a habeas petition?

Under the abuse-of-the-writ doctrine, a 2254 petitioner generally is barred from asserting claims that were not raised in a prior 2254 petition. See McCleskey v. Zant, 499 U.S. 467, 493 (1991). However, a habeas petitioner's failure to raise a claim in a prior petition may be excused if he can demonstrate either cause and prejudice or that a fundamental miscarriage of justice would result from the court's failure to entertain his claims. Id. at 494-95. A fundamental miscarriage of justice occurs when a constitutional violation probably has caused an innocent person to be convicted of the crime. Id. at 494.