29 C.F.R. § 452.54

(a) The reasonableness of applying a newly adopted restriction on candidacy retroactively depends in part upon the nature of the requirement. It would be unreasonable for a labor organization to enforce eligibility requirements which the members had no opportunity to satisfy. For example, it would not be reasonable for a union to apply a newly adopted meeting attendance requirement retroactively since members would have no opportunity to comply with such requirement prior to its effective date. 33 When such a rule is in effect the membership is entitled to advance notice of the requirements of the rule and of the means to be used in verifying attendance. It would not be unreasonable, however, for a union to adopt and enforce a rule disqualifying persons convicted of a felony from being candidates or holding office.

(b) It would not be proper for a labor organization to amend its constitution after an election to make eligible a person who had been elected but who was not eligible at the time of the election.