If you have been arrested, or have been a witness to arrests, it is very important to keep a personal and detailed written record or tape record of any incidents you have with the police, including the time and date of the incident. If you have been assaulted, it is important that you see a doctor as soon as possible and ensure that the doctor records your injuries and what happened.
Take photos if the injuries are visible. If someone else takes photos of your injuries, you may need to call them as witnesses, so make sure you have their contact details. You should also record the names and contact details of any witnesses to the assault, and of the people who saw you immediately before and after the incident. Do not notify the police that you have made these records.
There is no law that prevents you from video-taping any events or taking photographs while protesting if these events are taking place outdoors.