Remember, if a police officer stops you:

1. "Am I being detained?"
-- If no: Walk away.
-- If yes:
2. "I request a lawyer be present before I answer any questions. I am exercising my right to remain silent."

Then do so. If taken to jail, the only words out of your mouth should be "I refuse to answer any questions without my lawyer present." and/or "Let me contact my lawyer now."

If you don't have a lawyer's number memorized, write it in sharpie on your arm before attending a protest.