My bf worked at a company in Alabama for 6 years and now his boss is retroactively taking away vacation for everyone.

THe boss had ot pay out on a person who accumulated vacation and she fired, so now she''s changing the vacation policy, which is fine, but she''s retroactively doing so (A year or two back) and now everyone owes negative 100 or more hours to her. People used their earned vacation hours in good faith and now they are being chained down for it. Is it legal for her in Alabama to suddenly punish people for using a policy she had in place?? What can the people being wrongly punished do?