I’m sure that is going to have to be worked out in the courts. My guess, and I used to practice employment law, is that it will be handled just like alcohol. Employers can’t take any adverse action just for using, without proving an actual impairment on the job. Of course some jobs, like DOT trucking companies, railroad companies, etc., can always have random drug tests of the employees.
I was just pondering. Might need some as tax increases, etc will mean I can’t afford my life. Sigh.