2 weeks pay
I'm not sure if this is a law or not.
Most organizations that I've worked for have a policy that states that you will give a 2 week notice unless you're in management, then you'll give a 1 month notice. That's nothing they can enforce, but gives them an out to mark you as a "no hire" in case they don't like you and you want to come back.
In those organizations when someone gave a 2 week notice, but were told that they should leave immediately, then the employer had to pay the 2 weeks pay becuase of the policy stating that they had to give the 2 weeks notice. If they don't, then the employee could sue. Not because it's law, but because the employer didn't follow their own policy.