In Clark, Attorney General, et al. v. Gabriel (1968), the U.S Supreme Court ruled in favor of a prisoner's right to file habeas corpus petitions without prepayment of fees or costs associated with such filings. The case involved John J. Gabriel who was serving time for murder and attempted to file a writ of habeas corpus but was denied because he could not afford the filing fee required by federal law at that time. He argued this requirement violated his constitutional rights under the Fourteenth Amendment’s Equal Protection Clause as it discriminated against indigent prisoners like him who couldn't afford these fees. The court agreed with Gabriel stating that everyone has an equal right to access courts regardless of their financial status and struck down any laws requiring payment before allowing prisoners to exercise their legal rights through habeas corpus petitions.

In the dissenting opinion for Clark, Attorney General, et al. v. Gabriel, Justice Hugo Black argued that the majority's decision to grant a writ of habeas corpus was incorrect because it failed to respect the findings and conclusions of state courts. He believed that there was no constitutional violation in this case as he saw no evidence suggesting that Gabriel's confession had been coerced or obtained through improper means by law enforcement officials. Furthermore, Justice Black criticized the majority for overstepping its bounds and intervening in matters traditionally left to state courts without any clear justification or compelling reason to do so.