Advocates for California sex workers are seeking to legalize the world's oldest profession.

A federal lawsuit filed March 4 seeks to strike down the California law criminalizing prostitution as an unconstitutional violation of equal protection and free speech rights. The lawsuit was filed by the San Francisco-based advocacy group Erotic Service Providers Legal, Education and Research Project along with three women who say they want to work legally as prostitute in California. A disabled man who says he wants to legally pay for sex is also a plaintiff.

The California Attorney General's office didn't immediately return a call for comment.

The group says it raised $30,000 last year to hire an attorney and file the lawsuit. It's seeking an additional $30,000 to pay for the continued litigation.