> You decide it should be criminalized before you identify any harms?

No. We have a measure of the harms. We haven’t balanced them for sentencing. Again, deciding something should be illegal doesn’t require obsessing over the sentence ex ante.

> Maximum sentence for mugging is 30 years

Not the norm, either for maximums [1] or usual sentences.

[1] https://en.wikipedia.org/wiki/Robbery_laws_in_the_United_Sta...