Street preachers in New Orleans are fighting a city ordinance banning "aggressive solicitation" on Bourbon Street.
The new rule restricts religious or political speech after dark on the popular street, known for being home to racy Mardi Gras celebrations.
Assembly of God Pastor Paul Gros said police asked him to leave or face arrest while he preached on Bourbon Street with his wife in May.
Although he left without being taken into custody, several other preachers were arrested about a month ago during a gay pride festival.
The American Center for Law and Justice is now representing Gros, in hopes of putting an end to the ordinance.
"A government body may not exclude or restrict the speech of private parties for the sole reason that the speech is religious or contains a religious perspective," ACLJ attorneys wrote in a letter to the city. "This is a fundamental proposition of constitutional law."
The city council adopted the ordinance in October 2011. Violating the ordinance can lead to up to six months in jail and a $500 fine.