In Garner v. Jones, the United States Supreme Court laid out rules for lower courts to determine whether granting parole boards the discretion to change retroactively the frequency of parole reconsideration hearings would violate the Ex Post Facto Clause. The Court held that a prisoner challenging one of these statutes must produce certain evidence that the statute "created a significant risk of increasing his punishment."
Renjel, Robert A.
"Garner v. Jones: Restricting Prisoners' Ex Post Facto Challenges to Changes in Parole Systems,"
Mercer Law Review: Vol. 52
, Article 10.
Available at: https://digitalcommons.law.mercer.edu/jour_mlr/vol52/iss2/10