Habeas corpus is the correct procedure for persons who claim they are wrongly imprisoned.  For any other civil rights claim in federal court by a state prisoner, the correct procedure is a suit under the civil rights law, 42 U.S.C. §1983.  The line between the two is not always clear.

Today the U.S. Court of Appeals for the Ninth Circuit, sitting sort of en banc, decided Nettles v. Grounds, No. 12-16935:

Damous Nettles, a prisoner serving a life sentence in California prison, appeals the district court's dismissal of his habeas petition for lack of jurisdiction. The petition challenged a disciplinary violation on constitutional grounds and claimed that the failure to expunge this violation from his record could affect his eligibility for parole. We conclude that because Nettles's claim does not fall within the "core of habeas corpus," Preiser v. Rodriguez, 411 U.S. 475, 487(1973), it must be brought, if at all, under 42 U.S.C. § 1983.

Judge Ikuta wrote the opinion, joined in full by Judges Rawlinson, Clifton, Callahan, and Randy Smith.  Judge Hurwitz concurred in part.  Judge Berzon dissented, joined by Chief Judge Thomas and Judges Fletcher, Murguia, and Nguyen.