Assuming that the reason they will not re-hire you is solely because you resigned (and not because some other reason like your race or age), then a Florida employer is within its right to do that. Florida like most states is an employment at will
state - meaning you can be disciplined or put on a do not hire list for any reason that is not otherwise a violation of law. These exceptions are the civil rights protections (e.g., age, race, sex, religion), violations of public policy
(e.g., fired for attending jury duty
, for refusing to break the law, for reporting illegal activity by the employer (aka a "whistleblower
violation"), or having some contractual right to a just cause employment (meaning the employer cannot terminate you without industrial due process - which basically insures a fair and accurate investigation and decision). Without any of these exceptions, courts find that the employer has a legitimate business right to operate its business however it sees fit and the court will not second-guess the employer. These policies and decisions may in fact be awful and clearly not fair or even make good business sense. However, they are not ultimately unlawful.
Being put on a "do not re-hire" list is not illegal unless it is combined with one of these exceptions. It does not appear that you have any of these exceptions. So I'd have to opine that it is not illegal.
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