I address some of those criticisms directly in the post, though. It is quite a leap in logic to say that use (which is all the tests can determine) indicates addiction. As I pointed out, people with legitimate problems are pretty obvious and if no problem is obvious, there is no problem to be concerned with.

As to the idea that a worker has a choice, I would point to the paragraph where I cover that issue. No one is forcing a person to take a particular job but our drive to do things like eat and have shelter combined with the ubiquity of drug tests really removes a person's "choice" in the matter. Most people will trade the right to govern their bodies in order to survive but that does not make forcing the choice on them any more ethical.

Over all, I would take a merit based approach. I would rather have a high worker who does his or her job effectively (and there are many) than an incompetent sober one (there are plenty of those too).