Easy, the same one that exists for doctors, attorneys, plumbers, etc.. a requirement that they be bonded and insured individually. The one’s who repeatedly step on their dicks will be unable to afford the insurance eventually. And yes, end qualified immunity, a legal decision that was made up out of thin air.
I don’t personally have a contrary opinion, IF it could be done.
But I fear it would drastically cut the numbers of people willing to become cops when so many are leaving already. Criminals are getting away with so much now, it must be very demoralizing to decent people who would like to go into LE. We won’t have many more if we lay even more demoralization and risk on them...