Because in a free society, a system that stops crimes half of the time and arbitrarily denies people their rights half the time is considered unjust. Would it

Because in a free society, a system that stops crimes half of the time and arbitrarily denies people their rights half the time is considered unjust. Would it be okay for police to stop suspicious-looking people on the streets and ask them for ID and run background checks if it caught criminals 50% of the time?