How would you go about reducing the overall crime level while preserving civil rights?
Get to the root of the problem by insuring that people are well educated enough, that the job market is stable enough, and that the minimum wage is high enough, for people to provide for themselves and live productive lives as something more than petty consumers and/or criminals. After that you could crack down on the crime that can’t necessarily be solved that way, i.e. organized crime, racketeering, gang violence etc. and focus on eliminating cultural elements and criminal organizations that lead people to commit crimes, rather than using the band-aid solution of simply punishing the individual perpetrators.