should employers get a say in what you do off the clock?

**this is in terms of things like smoking weed or using a drug that does not cause dependency**

if employers won’t fire you for using alcohol on your own time, is it right to fire you for using other drugs (that are legal or not hard drugs)? especially if you need to do tests in order to find out if they were used in the first place?

keeping in mind, we are assuming you can still do your job fine and none of it gets in the way of your job performance.

(sorry if my question doesn’t make a lot of sense, i can clarify if needed in the comments).