Whether a retroactive reduction in statutorily available good-conduct gain time can violate the Ex Post Facto Clause even though the prisoner has no vested right to future credits.
Holding
Yes. A law violates the Ex Post Facto Clause when it is retrospective and makes the punishment for an earlier crime more onerous; the prisoner need not show that a vested right was impaired.
Reasoning
The Ex Post Facto Clauses prohibit laws that impose punishment for conduct that was not punishable when committed or that add punishment beyond what the law then prescribed. The prohibition serves both fair notice and structural restraint: people may rely on the penal consequences attached to their acts, and legislatures may not retroactively increase punishment in an arbitrary or vindictive way.
The Court's test has two elements. The challenged penal law must be retrospective, meaning that it applies to events occurring before enactment, and it must disadvantage the affected offender. A change that is merely procedural, without increasing punishment or changing the elements or proof of guilt, does not offend the Clause.
Florida's focus on vested rights was misplaced. Vested-right analysis may matter under due process or contract doctrines, which protect established entitlements, but the Ex Post Facto Clause asks a different question: whether the legislature retroactively made the penal consequences of completed conduct more severe. Thus, even a benefit granted by legislative grace may not be retrospectively reduced if doing so increases punishment.