A federal judge Thursday turned down a request by five nudism activists for a temporary restraining order blocking a San Francisco ban on nakedness on public streets, sidewalks and transit vehicles.

U.S. District Judge Edward Chen said in a written ruling that a motion filed by the activists Friday was not accompanied by evidence, was "lacking in details" and was "lacking in any substantive legal argument in support."

The five plaintiffs filed the motion for a temporary restraining order together with an amended version of a lawsuit challenging the ban.

The ban went into effect on Feb. 1. Three days before that, Chen dismissed an earlier version of the lawsuit that claimed the measure violated the right of free speech. Chen said nudity is not protected speech because it is not "inherently expressive."

The amended lawsuit claims police are enforcing the ban in an unconstitutionally discriminatory way by targeting the plaintiffs in events they organize, but not others who go nude in other events.

In addition to refusing the request for a temporary restraining order, Chen declined to set a hearing on a motion for a preliminary injunction, which would be the next step in the case, for the same reasons of lack of evidence and detail.

But he said the plaintiffs could refile a request for a preliminary injunction if the motion is "properly briefed and supported."

The plaintiffs in the lawsuit are San Francisco residents Mitch Hightower, George Davis, Russell Mills and Russell "Trey" Allen and Berkeley resident Oxane "Gypsy" Taub.

Their lawyer, Cristina DeEdoardo, said she plans to file a new request for a preliminary injunction.

"We're disappointed but we will continue the struggle," she said.

The law enacted by the Board of Supervisors last year bans public nudity on streets, sidewalks and transit stations and vehicles. It makes exceptions for young children and participants in parades and fairs that have received permits.

Separate city laws restrict nudity in restaurants, public seating areas and parks.