Sec. 4. (a) If a subsequent application for writ of habeas corpus is filed after final disposition of an initial application challenging the same conviction, a court may not consider the merits of or grant relief based on the subsequent application unless the application contains sufficient specific facts establishing that:
(1) the current claims and issues have not been and could not have been presented previously in an original application or in a previously considered application filed under this article because the factual or legal basis for the claim was unavailable on the date the applicant filed the previous application; or
(2) by a preponderance of the evidence, but for a violation of the United States Constitution no rational juror could have found the applicant guilty beyond a reasonable doubt.
(b) For purposes of Subsection (a)(1), a legal basis of a claim is unavailable on or before a date described by Subsection (a)(1) if the legal basis was not recognized by and could not have been reasonably formulated from a final decision of the United States Supreme Court, a court of appeals of the United States, or a court of appellate jurisdiction of this state on or before that date.
(c) For purposes of Subsection (a)(1), a factual basis of a claim is unavailable on or before a date described by Subsection (a)(1) if the factual basis was not ascertainable through the exercise of reasonable diligence on or before that date.