One of the most prominent groups advocating for stricter immigration went to court Wednesday to demand a judge order the Southern Poverty Law Center to stop labeling it a “hate group,” accusing the self-described watchdog of running an illegal racket to silence political opponents.

The Center for Immigration Studies says the SPLC’s accusations that it is racist and anti-immigrant are wrong and have cost the nonprofit support and financial backing by scaring people away from doing business with the center.

The center brought its challenge to U.S. District Court for the District of Columbia by filing a civil complaint under the Racketeer Influenced and Corrupt Organizations (RICO) Act against SPLC President Richard Cohen and Heidi Beirich, who runs the group’s Hatewatch blog.

Mark Krikorian, the Center for Immigration Studies executive director, says his organization doesn’t meet the SPLC’s definition of a hate group and the Alabama-based watchdog knows it but persists anyway — which he said was evidence of the racket.

“SPLC and its leaders have every right to oppose our work on immigration, but they do not have the right to label us a hate group and suggest we are racists,” he said. “The Center for Immigration Studies is fighting back against the SPLC smear campaign and its attempt to stifle debate through intimidation and name-calling.”