Have an associate who can take a good video of the encounter with audio, or quickly recruit a bystandier who can:
don't raise your voice when talking to the disruptor;
make sure any physical contact is initiated by the disruptor;
don't use what you believe to be excessive force;
in a loud voice, tell the disruptor to stay down on the floor/ground until police arrive;
immediately email the video to the address on the business card of the responding LEO;
do not talk to the press or anyone you believe is associated with the disruptor, etc
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