In Bankes v. Simmons, 265 Kan. 341, 963 P.2d 412 (1998), the amendment to the regulation in question forced the prisoners to earn good time credits previously awarded automatically under the old law. For each credit not earned, their conditional release dates were extended. Additionally, the amended regulation actually forced them to engage in a rehabilitation program or risk the loss of good time credits which would have automatically been earned under the old system. To the extent the amendment adversely affected the prisoners' conditional release and parole eligibility dates, the new law constituted an ex post facto violation. 265 Kan. at 353.