(a) Whenever a State prisoner under capital sentence files a petition for habeas corpus relief to which this chapter applies, the district court shall only consider a claim or claims that have been raised and decided on the merits in the State courts, unless the failure to raise the claim properly is - (1) the result of State action in violation of the Constitution or laws of the United States; (2) the result of the Supreme Court's recognition of a new Federal right that is made retroactively applicable; or (3) based on a factual predicate that could not have been discovered through the exercise of due diligence in time to present the claim for State or Federal post-conviction review. (b) Following review subject to subsections (a), (d), and (e) of section 2254, the court shall rule on the claims properly before it.