As for the cops who mistakenly build cases against innocent folks; they should at least lose their jobs, and possibly even face prosecution, IMO. Locking up even one innocent person is too many. If there were even a shred of TRUE accountability in government and law enforcement, these things would happen at a much lesser rate.
Expecting perfection is an unrealistic goal, minimizing mistakes, a realistic goal -- do you similarly believe that any doctor who has ever made a mistake resulting in serious injury or death also be barred from working in the medical profession?