N.D. Cent. Code § 40-45-01

Any city having a population in excess of five thousand inhabitants according to the last official federal census and having an organized and paid police department may provide funding for the purpose of creating and maintaining a police pension fund from revenues derived from its general fund levy authority. Any city having established by law a police retirement system based upon actuarial tables may provide funding for the police pension fund from revenues derived from its general fund levy authority.