There is a problem with profing if minimum-wage laws "result in unemployment" (no one talks about the laws destroying jobs, but that should happen before people become official unemployment statistics).(posted 7203 days ago)How can one proofe anything if politicians increase the minimum wages just a little. One need not only a huge sample (statistics, big samples are needed to measure small changes) and preferantly a static environment. It is not easy to gain statistical significance: http://www.economist.com/finance/displayStory.cfm?story_id=2384590 and unfortunately people believe these unsignificant reports (against all reason as well).
The Haitian example is a good natural experiment, and I hope that no one will dare to try it again.