Quick search by citation:

28 U.S. Code § 2264 - Scope of Federal review; district court adjudications

(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—
the result of State action in violation of the Constitution or laws of the United States;
the result of the Supreme Court’s recognition of a new Federal right that is made retroactively applicable; or
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.
Following review subject to subsections (a), (d), and (e) of section 2254, the court shall rule on the claims properly before it.
Statutory Notes and Related Subsidiaries
Effective Date

Section applicable to cases pending on or after Apr. 24, 1996, see section 107(c) of Pub. L. 104–132, set out as a note under section 2261 of this title.