Setting the stage for an appellate court showdown, a federal judge in Wisconsin has struck down as unconstitutional a state law that reportedly is the only one in the nation banning prison inmates who were born biologically male but identify as female from receiving hormone therapy.

The law violates the equal protection clause and is an unconstitutional form of cruel and unusual punishment, explained U.S. District Judge Charles Clevert in a brief written order (PDF) yesterday. That is because it denies hormone therapy without considering individual inmates' medical needs or the judgment of their doctors, according to the Milwaukee Journal Sentinel.

Outraged legislators who drafted the law promised to urge the state attorney general to appeal Clevert's ruling. If it stands, the state likely will have to pay substantial attorney fees to the American Civil Liberties Union of Wisconsin and the Lambda Legal national gay rights group, which represented the plaintiff inmate group, reports the Associated Press .

"It's a victory for these inmates who have a condition that is misunderstood and vilified for political purposes that can be very serious," says ACLU attorney Larry Dupuis, who represents the plaintiffs. "To take away a whole class of treatment just because it's politically disfavored is not constitutional."

It isn't clear from Calvert's order whether it is also unconstitutional for the prison system to ban surgical treatment of transgendered inmates. However, he has promised a more detailed opinion soon.