Michael J. Steinberg, legal director for the ACLU of Michigan, addresses the media beside Insane Clown Posse members Joseph Bruce, aka Violent J, center, and Joseph Utsler, aka Shaggy 2 Dope. AP Photo/Carlos Osorio

The hip-hop duo Insane Clown Posse and the American Civil Liberties Union have sued the U.S. Department of Justice and the FBI, accusing them of wrongly identifying the group's fan base as a criminal gang, violating its free speech rights.

The Michigan-based Insane Clown Posse is known for its "controversial, rebellious and provocative" music that often uses harsh themes and language, according to the lawsuit, which was filed in U.S. District Court in Detroit on Wednesday.

Many of the duo's estimated 1 million fans, known as Juggalos, paint their faces to look like clowns and display a logo of a hatchet man on their clothes and jewelry, according to the lawsuit.

In a press release, the Michigan chapter of the ACLU said that Juggalos "are not an organized fan club, but a group of people who bond over the music and a philosophy of life, much like 'Deadheads' bonded around the Grateful Dead."

The statement continued, "The Juggalos are fighting for the basic American right to freely express who they are, to gather and share their appreciation of music, and to discuss issues that are important to them without fear of being unfairly targeted and harassed by police."

The gang designation has caused the Juggalos "significant harm, including repeated police harassment and denial of employment," according to the complaint.

"You cannot brand over a million Juggalos as gang members without any evidence," Rana Elmir, spokeswoman for the ACLU, told Al Jazeera. "Designating fans as a criminal enterprise is in violation of their constitutional rights to expression and association."