The New Jersey Smoke-free Air Act, which prohibits smoking in restaurants, bars, private office buildings and other indoor places, is being fought in court by hospitality industry leaders. On April 13 two days before it takes effect a federal judge in Trenton will hear arguments on their request to postpone its implementation until their lawsuit challenging a casino exemption is heard. In the meantime, bar and restaurant owners are awaiting the state’s publication of rules that spell out the specifics of the ban and its enforcement. ``What I hear is a lot of questions,’’ said Deborah Dowdell, executive director of the New Jersey Restaurant Association, one of the groups challenging the ban in court. The lack of rules has left ``thousands of small businesses that don’t know what to do.’’