To add a bit more - there are no city/county criminal laws in the United States, only state and federal. But we have Federal, State, City, and County law enforcement officers. So Denver is working to de-prioritize/“decriminalize” for in-city law enforcement officers. I imagine state police and federal officers would not pay too much attention to this if it goes through.
Also, a city has no ability to decriminalize something, as that would have to be done by the state legislature or a statewide vote. So this is really not “decriminalizing” at all... the initiative itself uses the word “deprioritize”: https://static1.squarespace.com/static/5bb4f9c27046803ce123a...
Edit: word choice.