In the Chauvin case all three of the bystanders were sent to prison by federal courts specifically for civil rights violations stemming from their failure to intervene as Derek Chauvin murdered George Floyd in front of them.
If a cop violates your rights, you just have to pray the DA will prosecute criminal charges. But you still won’t get an monetary damages from the cop. You might talk the state into settling.
Cynically this probably only happened in the Chauvin case because the state would have been burned to the ground otherwise.
Maybe folks need to get in the street more...