How should LEA catch/prevent crime without mass surveillance?

Privacy is a human right but our corrupt governments are stealing it away from us. They use keywords such as pedophiles, terrorists, internet trolls as their excuse for mass surveillance.

If we actually managed to win the war resulting in LEA not being able to track all our offline and online activity, then how should they do their job?

In privacy discussions we focus mostly on the facts that privacy is a human right and we need it to have …

crime mass surveillance privacy surveillance