This month, black, Muslim and Latino activist groups helped shut down a Trump rally in Chicago. More audacious and often risky protests followed. Over the weekend in Arizona, demonstrators blocked a road leading to a Trump rally, and another protester was punched while being ejected from a Trump event.

It’s unclear whether any left-leaning activists will be able to breach security to protest inside the Republican National Convention, but Trump has said his supporters might riot in Cleveland if establishment Republicans persuade GOP delegates to nominate a different candidate.

But protesters may be even more worried about the people tasked with controlling the crowd. Much of the security outside the convention, which will include police from multiple agencies, will fall under the authority of the Cleveland Police Department, which has come under federal scrutiny for its repeated use of “unreasonable and unnecessary force,” in the words of a 2014 Justice Department investigation.