decriminalization

Short definition from Wiktionary

Noun

1. 1
   The act of making an activity or substance no longer criminalized (no longer a crime, subject to criminal penalties, to perform or possess). (Compare legalization, which often implies regulation.)
2. 2
   The act of ceasing to treat a person as a criminal, by making their activities legal or no longer subjecting them to the criminal justice system (but instead possibly the mental healthcare system, etc).