Aren't we all missing the idea that companies have a right to drug test employees and potential hires, and not hire them? Some may cry discrimination, but discrimination is extremely important to our decision making process. If someone does not meet your criteria, TS! If you want that job and know they test, be a responsible adult and STOP!
I think once again this will all boil down to personal responsibility and accountability. You take your life in your hands, or you hand it off to someone else. If you've done the hand off, you probably shouldn't talk policy anymore. If you're a responsible person, welcome aboard. The only diversity we care about is diversity of ideas. Everything else is based on merit.