In Delo, Superintendent, Potosi Correctional Center v. Stokes (1989), the U.S Supreme Court ruled on a case involving an inmate's right to access legal resources while in prison. The respondent, Stokes, was a prisoner who had been denied access to certain legal materials by the petitioner and superintendent of his correctional center. He argued that this denial violated his constitutional rights under the Fourteenth Amendment's Due Process Clause and sought damages for these alleged violations. The court held that prisoners have no absolute right to any specific law library or legal assistance program; instead they are entitled only to adequate tools for challenging their sentences or conditions of confinement. It also noted that inmates must show actual injury from being unable to pursue a non-frivolous claim before they can receive compensation for such denials. This decision clarified how courts should evaluate claims about inadequate access to legal resources in prisons: it is not enough simply for an inmate to allege he has been denied some particular resource; he must demonstrate how this denial has actually harmed him.

In the dissenting opinion for Delo, Superintendent, Potosi Correctional Center v. Stokes (1989), Justice Blackmun argued that the majority's decision was a departure from established precedent regarding habeas corpus petitions. He contended that under previous rulings, federal courts were obligated to review state court decisions de novo when constitutional rights were at stake. In this case, he believed that Stokes' Sixth Amendment right to effective counsel had been violated due to his attorney’s failure to investigate and present mitigating evidence during sentencing in his capital murder trial. Furthermore, Justice Blackmun criticized the majority for ignoring significant procedural errors made by the Missouri Supreme Court in its handling of Stokes' appeal and post-conviction proceedings which could have affected their judgment on whether or not there was ineffective assistance of counsel.