When did we try this?
I believe we pretty quickly went from government mandated discrimination, to government mandated reverse discrimination/affirmative action.
I had actually been thinking of "No Irish Need Apply" among other things, but then I looked it up and that turned out to be an English thing, and the commonly accepted ubiquity of it in America was a myth. So I'm gonna hold off until I've double checked the rest of the things I was thinking of. In the meantime, what exactly do you mean by government mandated discrimination and when are you saying it ended?
(And as Joshua notes, what country are we talking about here? I live in America, so that's what I was thinking of)
http://www.boingboing.net/2011/01/24/should-employers-be.html