The First Amendment to the U.S. Constitution protects “the freedom of speech” as well as “the right of the people peaceably to assemble.” So you have a constitutional right to demonstrate. Here’s some advice on how to exercise that right.
Here’s some additional practical information you might need:
And here’s some more general Know Your Rights information:
File a claim with ACLU-DC
Download the ACLU-DC Mobile Justice App before attending any events.