A group of nude protesters marched to their courthouse on Wednesday to file a lawsuit against the city and county of San Francisco.
They aim to stop city leaders from passing a law which would stop them appearing naked in public.
Under the law a first-time citation for nudity would mean a fine of up to $100. A second instance could lead to a $200 fine, while a third means a fine of up to $500 and the possibility of a year in prison.
The nudists say the proposed law violates their right to freedom of speech.
Scott Wiener, a city supervisor representing the Castro District, introduced the proposal which would stop backsides and genitals being exposed in public.
Exempt from the law would be naked breasts and children under five, as well as events permitted by the city - including the annual gay pride parade.
Former stripper turned stay-at-home mother of three, Gypsy Taub, is a plaintiff in the case.
She also hosts a television show called 'My Naked Truth' on which both she and her guests go unclothed.
The 43-year-old said: 'Being naked is a birth-given freedom, not a crime.'
At a public hearing related to the new law on November 5 Ms Taub stripped while speaking and was led away by security.
The board of supervisors will vote on the measure next week but the nudists asked for a preliminary injunction to stop the law being implemented if it is passed until after their claims that it violates their rights are considered by a judge.
One law which was passed last year saw nude citizens having to place a barrier, a towel for example, between their bare backsides and any public seats.