LAS VEGAS  During a tour of a Las Vegas Athletic Club gym, a prospective member, Todd Phillips, was struck by the fact that his wife was offered a cheaper sign-up rate than he was and that there was a special workout area for women.

A club representative dismissed his questions about the disparities, said Mr. Phillips, a lawyer who specializes in gender bias cases, so he filed a complaint with the Nevada Equal Rights Commission, arguing that price breaks and special areas of the health club for women only were illegal under state law. A ruling is expected shortly.

The complaint is perhaps the first anti-male gender bias case in Nevada, but civil rights panels and courts in several other states have grappled in recent years with what has come to be known informally as Ladies’ Night law because it often involves policies and practices among bars and nightclubs. Results have been mixed.

In 1985, the California Supreme Court ruled that such disparities were illegal, effectively ending them. Judges in Colorado, Iowa and Pennsylvania all have said that such events and offers are illegal, but state courts in Illinois and Washington have concluded that they are a permissible means of attracting desired customers.