LITTLE ROCK, Ark. (AP) — A legal advocacy organization has filed a lawsuit in federal court challenging an Arkansas state law that farm organizations have used to shield themselves from undercover investigations by animal rights groups.

Lawyers for the Animal Legal Defense Fund and other animal rights organizations filed the suit Tuesday against state Rep. DeAnn Vaught and her husband, who own a pig farm, and Peco Foods, an Alabama-based poultry farm with Arkansas facilities.

The suit argues that the 2017 law, which was sponsored by Vaught and bars undercover investigations at private business...