In Cooper v. Pate the Supreme Court relied upon civil rights. Another source of prisoners' rights arose from the Court's reliance on habeas corpus. The Latin phrase is an imperative meaning "Have the body …" with the rest of the phrase, "brought before me," implied. A writ of habeas corpus is therefore the command issued by one court to another court (or lesser authority) to produce a person and to explain why that person is being detained. Habeas corpus dates back to an act of the British Parliament passed in 1679. The U.S. Congress enacted the Judiciary Act of 1789 and gave federal prisoners the right to habeas corpus review. The Habeas Act of 1867 later protected the rights of newly freed slaves and also extended habeas corpus protection to state prisoners. The effective meaning of habeas corpus for prisoners is that it enables them to petition federal courts to review any aspect of their cases.

The Court also revisited habeas corpus in the 1960s. In Smith v. Bennett (365 U.S. 708, 1961), the Court ruled that states could not deny a writ of habeas corpus to prisoners who could not pay a filing fee. In Long v. District Court (385 U.S. 192, 1966), the Court ruled that a state must furnish prisoners, not otherwise able to obtain them, with transcripts of prior hearings. In Johnson v. Avery (393 U.S. 483, 1969) the Court emphasized the basic purpose of the writ of habeas corpus in enabling those unlawfully imprisoned to obtain their freedom. The case concerned whether the state could prevent inmates from helping each other file petitions. The Justices held that "it is fundamental that access of prisoners to the courts for the purpose of presenting their complaints may not be denied or obstructed." They ruled that until the state provides some reasonable alternative to assist inmates in the preparation of petitions for postconviction relief, it "may not validly enforce a regulation which absolutely bars inmates from furnishing such assistance to other prisoners." In Bounds v. Smith (430 U.S. 817, 1977) the Court further asserted that prison authorities must "assist inmates in the preparation and filing of meaningful legal papers by providing prisoners with adequate law libraries or adequate assistance from persons trained in the law."

Bounds did not create an abstract, freestanding right to a law library or legal assistance; rather it acknowledged the right of access to the courts. Inmates have to prove that the alleged shortcomings in the prison library or legal assistance program hindered their efforts to pursue a nonfrivolous legal claim. In addition, the Court relied on a constitutional principle that:

prevents courts of law from undertaking tasks assigned to the political branches.… It is the role of courts to provide relief to claimants, in individual or class actions, who have suffered, or will imminently suffer, actual harm; it is not the role of courts, but that of the political branches to shape the institutions of government in such fashion as to comply with the laws and the Constitution.… If—to take another example from prison life—a healthy inmate who had suffered no deprivation of needed medical treatment were able to claim violation of his constitutional right to medical care…, simply on the ground that prison medical facilities were inadequate, the essential distinction between judge and executive would have disappeared: it would have become the function of the courts to assure adequate medical care in prisons.

Bounds did not guarantee prison law libraries and legal assistance programs. They are only "one constitutionally acceptable method to assure meaningful access to the courts." There can be "alternative means to achieve that goal." An inmate has to show that access to the courts was so "stymied by inadequacies of the law library that he or she was unable even to file a complaint."

Some twenty-four years after Bounds, in Shaw v. Murphy (532 U.S. 223, 2001), a more conservative Court ruled that Kevin Murphy, incarcerated in a Montana state prison, did not "possess a special First Amendment right to provide legal assistance to fellow inmates." Murphy was punished after he attempted to intervene in a process in which a fellow prisoner was charged with assaulting a guard. Much had changed since the 1970s. Murphy was employed as an "inmate law clerk," and he provided legal assistance to other inmates. Murphy had applied to assist another prisoner, Pat Tracy, but the prison had denied the request because Murphy, a high-security inmate, could not meet with Tracy, a maximum-security inmate. Murphy persisted nonetheless, investigated the case on his own, and wrote a letter to Tracy offering his help. Murphy's punishment arose from this action.