This is an old thread and there really isn't much in today's news that calls out for adding another post. But there is one point that isn't made often enough.
When government makes laws that require a license, or a certificate in order to engage in some act (marriage, opening a business, being a beautician or manicurist or therapist, etc.) - it is really a prohibition. It is valid for a government to prohibit any act that violates the individual rights of another. But with licenses, what is prohibited is NOT an act that violates another's individual rights, and therefore it is a direct decrease of liberty.
A license or occupational certification is something where regulators create specific requirments (pay a fee, get a blood test, be a certain age, pass an examine, etc.) and everyone who doesn't comply with whatever the regulations call for is prohibited from taking those actions. It takes an area of actions - actions that have nothing to do with theft, fraud or initiation of force - and makes them illegal unless the person gets the state's permission (the license). In effect, converting a right into a limited permission and reinforcing the foul idea that the state has all the rights while people need permissions.
If one woman wants to pay another woman to braid her hair, that other woman is prohibited from doing the hair-braiding unless she has taken courses, passed tests, and acquired a license from the state. Once, not that long ago, there were states in the South that would not permit the marriage of an inter-racial couple. Only a government required licenses make it possible for the government to destroy liberty in that fashion. (The couple could just co-habitate, but that was also illegal at the time).
There is a valid concept behind a non-government issued license or certification. It can be evidence of a competence provided by a trusted authority. But that's a different animal, and we won't see many of those while government steps in a ruins the market for valid licenses or certifications.
(Edited by Steve Wolfer on 10/10, 1:32pm)