Stop-and-frisk was only new because the newly expanded federal civil rights in the early 60s would have made the long-standing police practice illegal without a special exception. It's not like the cops discovered hassling people based on stereotypes in 1968.
How would a new legal justification for something cops have been doing forever suddenly cause a crime reduction? You'd have a much better case arguing that the semi-professionalization of the police in the aftermath of Warren court rules complicating police procedure caused it.
I'm not sure I understand your larger point at all: Singapore is a police state and people there seem to be pretty on board with it, so until everywhere is like Singapore we shouldn't do anything about it?
How would a new legal justification for something cops have been doing forever suddenly cause a crime reduction? You'd have a much better case arguing that the semi-professionalization of the police in the aftermath of Warren court rules complicating police procedure caused it.
I'm not sure I understand your larger point at all: Singapore is a police state and people there seem to be pretty on board with it, so until everywhere is like Singapore we shouldn't do anything about it?