This valuable resource from the ACLU, Know Your Rights: What To Do If Your Rights Are Violated at a Demonstration or Protest, covers what you should know before heading out to exercise your constitutionally protected right to protest, as well as what to do if your rights are violated when you do.

Two of the most important pieces of information:

Q.What do I do if I get stopped by the police?
A. Stay calm, be polite, and don’t run. Don’t argue, resist, or obstruct the police, even if you are innocent or you believe that the police are violating your rights. In some states, you must give your name if asked to identify yourself, but you do not have to provide an ID or other paperwork. Make sure to keep your hands where police can see them. Point out that you are not disrupting anyone else’s activity and that the First Amendment protects your actions. Ask if you are free to leave. If the officer says yes, calmly and silently walk away.

Q.And if I’m under arrest?
A. Do not resist arrest, even if you believe the arrest is unfair. If you are under arrest, you have a right to ask why. Otherwise, say you wish to remain silent and ask for a lawyer immediately. Don’t give any explanations or excuses. Don’t say anything, sign anything, or make any decisions without a lawyer. You have the right to make a local phone call, and if you’re calling your lawyer, police are not allowed to listen.

You also have the right to take pictures. More about that in Know Your Rights: Protesters & Photographers and in this video, both also from the ACLU:

Prepare also by planning for your digital security when you protest. The Electronic Frontier Foundation (EFF) has a very helpful set of suggestions:

  1. Enable full-disk encryption on your device
  2. Remove fingerprint unlock
  3. Take photos and videos without unlocking your device
  4. Install Signal
  5. Read [the EFF’s] Surveillance Self Defense (SSD) guide for street-level protests
  6. Use a prepaid, disposable phone
  7. Back up your data
  8. Consider biking or walking to the protest
  9. Enable airplane mode
  10. Organizers: Consider alternatives to Facebook and Twitter

See the full details in their Digital Security Tips for Protesters guide.

Be physically prepared for the possibility of arrest or detainment.

  • Wear clothes which are warm enough and comfortable shoes for extended standing.
  • Carry a water bottle and some snacks.
  • Tuck a big garbage bag into your coat pocket; it can come in handy for rain protection, be used as a windbreaker, or give you clean, dry seating.
  • Consider who you’d call if you are arrested and need a lawyer (or need someone to find you one); then memorize that phone number since your phone may be taken from you or have dead batteries.
  • Review any tips sent by protest organizers to see if they have additional recommendations for you to follow for this event.
  • Make sure some friends or family who won’t be at the protest know where you’re going and what you want them to do if you don’t check in afterwards as planned (or if they hear you’ve been arrested or detained).