Probably a place who works with the government. Technically federal contractors are required to develop a plan, not test for pot. However, I would say a majority interpret that requirement as just do the testing. Still, it's usually pre-employment; not random. There's no way you would "lose a career" over it, unless, like I said you had clearance or something. I've also heard companies say: muh well our ditch diggers have to get tested so so do the engineers. Obviously that's only a problem if you work in a place that also digs ditches.