If you do that, you will have less jobs, and more competition for them. The average wage in law enforcement is $18. If I was in law enforcement, I would want to apply to McDonalds, or wherever, for $15. And they would probably accept me over some 18 year old.

In cities, like SF and NYC, you can raise the minimum wage maybe to 15, but federally or state-wide it would be a disaster policy.