WASHINGTON (AP) — The Supreme Court on Monday allowed a lawsuit to go forward against a Black Lives Matter activist who led a protest in Louisiana in which a police officer was injured. Civil rights groups and free speech advocates have warned that the suit threatens the right to protest.

The justices rejected an appeal from DeRay Mckesson in a case that stems from a 2016 protest over the police killing of a Black man in Baton Rouge.

At an earlier stage of the case, the high court noted that the issue was “fraught with implications for First Amendment rights.”

The justices did not explain their action Monday, but Justice Sonia Sotomayor wrote a brief opinion that said lower courts should not read too much into it.

The court’s “denial today expresses no view about the merits of Mckesson’s claim,’' Sotomayor wrote.

At the protest in Baton Rouge, the officer was hit by a “rock-like” object thrown by an unidentified protester, but he sued Mckesson in his role as the protest organizer.