In the case of Jones v. Cunningham, the U.S Supreme Court ruled in 1962 that a prisoner on parole remained "in custody" for purposes of federal habeas corpus law. The petitioner, Robert E. Jones was convicted and sentenced to prison in Virginia state court but later paroled under certain conditions which he alleged violated his constitutional rights. He filed a petition for writ of habeas corpus with a Federal District Court arguing that these restrictions constituted illegal detention or imprisonment by the State Parole Board's Superintendent, B.A Cunningham. The lower courts dismissed his application stating that since he was not physically confined, he wasn't "in custody". However, upon appeal to the Supreme Court it held (by an 8-1 majority) that being on parole did constitute as being 'in custody' within meaning of federal habeas statute because even though physical confinement may be lacking, restraints imposed might still be so burdensome as to call for relief under this law.

In the dissenting opinion for Jones v. Cunningham, Justice Harlan argued that parole should not be considered as a form of custody under federal habeas corpus law. He contended that the majority's decision to extend habeas corpus rights to paroled convicts was an unwarranted expansion of federal jurisdiction and could potentially undermine state authority over their own penal systems. Furthermore, he expressed concern about potential abuse of this expanded right by prisoners seeking release from conditions imposed by parole boards rather than challenging their original convictions or sentences. In his view, such matters were better left to state courts and legislatures who are more familiar with local circumstances and needs in criminal justice administration.