(AP) — Officials in a small Nebraska city are preparing to enforce voter-approved illegal immigration rules, but opponents could file additional lawsuits after they take effect.

Fremont officials said Wednesday that police will start enforcing the measure 30 days after the results of a special city election are certified. Nearly 60 percent of voters decided Tuesday to keep the ordinance, which requires renters to get a $5 permit and swear they have legal permission to live in the U.S.

Amy Miller, of the American Civil Liberties Union of Nebraska, says her group will keep close tabs on the city and will consider a new lawsuit if tenants report discrimination. A federal appeals panel upheld the ordinance, but left an opening for lawsuits if people can show that it’s resulted in discrimination.