In the case of Board of Pardons et al. v. Allen et al., 1986, the U.S Supreme Court ruled that Montana's parole eligibility statute created a constitutionally protected liberty interest in parole release. The plaintiffs were inmates who had been denied parole and claimed their due process rights were violated because they weren't given an opportunity to be heard at their hearings or provided with reasons for denial. The court held that while there is no constitutional right to parole, once a state creates a statutory scheme for conditional release from prison, it cannot arbitrarily deny this without due process protections under the Fourteenth Amendment. This means prisoners must be given notice and an opportunity to respond before being denied parole under such schemes.

In the dissenting opinion for Board of Pardons et al. v. Allen et al., Justice O'Connor, joined by Chief Justice Burger and Justices Powell and Rehnquist, argued that Montana's parole statute did not create a constitutionally protected liberty interest in parole release. The dissenters contended that the majority misinterpreted Greenholtz v. Inmates of Nebraska Penal & Correctional Complex (1979), which held that a state creates a protectable expectation of parole only when its statutes use mandatory language to require release if certain designated findings are made. They believed Montana’s law was discretionary rather than mandatory because it allowed the board to deny parole even after finding good behavior and sufficient time served due to other considerations like seriousness of offense or public safety concerns. Therefore, they concluded there was no entitlement or legitimate claim under this statute warranting Due Process protection.