Texas Code of Criminal Procedure Article 11.07 Section 4(A)
Article 11.07, section 4(a) expresses the Legislature's clear intent that, absent unusual circumstances, a person may file only one application for habeas corpus relief which challenges the validity of a final conviction.
In Ex parte Torres, we determined article 11.07, section 4(a) was intended to limit a convicted person to "one bite at the apple." Ex parte Torres, 943 S.W.2d 469, 474 (Tex.Crim.App. 1997).
Article 11.07, section 4(a), in my opinion, is the response by the Legislature to the formerly common practice of an inmate filing an initial writ application claiming, for example, ineffective assistance of counsel and, if said initial writ is denied, filing subsequent "piece meal" writs attacking his conviction on various other grounds.
Nothing in the legislative history of article 11.07, section 4 indicates the Legislature intended its provisions to apply to an application alleging improperly-denied jail time credit as such an application is not, in any way, an attack on the validity of the conviction.
In Ex parte Evans, the Court recognized that not every application for habeas relief is a "challenge to the conviction" under article 11.07, section 4. Evans, 964 S.W.2d at 647.
In Ex parte Evans, the Court held that applicant's initial application challenging his parole revocation did not challenge the validity of his conviction; accordingly, his second application, which did challenge the validity of his conviction, was not barred by article 11.07, section 4, and the Court proceeded to address its merits.