As long as it's a mostly peaceful prostest, you're also allowed to set a few cars on fire and loot local businesses.
When I put the two sides on the scale - the things being protested and the damage done by protesters - typically it's very easy for me to write off a couple burned cars or broken windows, even if I'm not a fan of broken windows or burned cars. Because typically these protests in the US are over things like reckless killings.
As long as you say "I feared for my life", you're apparently also allowed to shoot random civilians if you're a cop.
Which is kinda why people are upset enough to set shit on fire.