Yes. Companies get to make decisions based on their regulations and signed contract with the employer. Then when/if those regulations and contract details chang, it does not mean you get your job back if you the rules governing your dismissal change. Remember when Josh Gordon had a second sample that was like 1 millionth of a % over the NFL's specified THC level - or whatever it was - and then within a couple months the threshold was elevated 80 or 800 fold? Josh still got a ban.