In different countries, the same law with the same penalty has different rates of law-breaking, so you can't necessarily draw a clear line of "this works, this

In different countries, the same law with the same penalty has different rates of law-breaking, so you can't necessarily draw a clear line of "this works, this doesn't" in every country/case. Yes, being harsh can have results. Does that mean its results are better than a different tact? The evidence of one method alone doesn't show you that, you have to experiment or study the same situation with both methods. There is evidence that, for example, treating prisoners more humanely and giving them trust and responsibility can lower recitivism rates, while there's also ample evidence to suggest that harsh fines and imprisonment for minor crimes creates greater recitivism. But this may vary by country and implementation.