Model aircraft hobbyists, research universities and commercial drone operators and investors have filed lawsuits challenging a government directive that they say imposes tough new limits on the use of model aircraft and broadens a ban on commercial drone flights.

The three lawsuits filed Friday ask the U.S. Court of Appeals for the District of Columbia to review the validity of the directive, which the Federal Aviation Administration issued in June. The agency said its move is an attempt to clarify what is a model aircraft and the limitations on their operation.

But attorney Brendan Schulman, who represents the groups, said the FAA directive is a backdoor imposition of new regulations, skipping the required federal rulemaking process. Those procedures require an opportunity for public comment and an analysis of potential costs.