There doesn't need to be a test case, because it's written in the law. A license is defined as a "transfer of rights", you can't transfer rights that you don't have.
The author (what's his authority, by the way?) agrees, though:
> Well, it can't sell "copyright licenses," as that is a misrepresentation over the rights that Getty Images has -- but if it wants to try to get people to pay for stuff that is otherwise available for free, that's Getty's prerogative.
His point is that he does not think that Getty was selling licences. However Getty's past behaviour (and I'm sure their own website since I'm sure that the T&C and the licence are attached to any sale) suggests that this is exactly what they were doing:
> The first one was brought by photographer Carol Highsmith, who sued Getty after Getty had sent a demand letter to her over her own images, which she had donated to the Library of Congress to be put into the public domain.
And yes, knowingly selling licences for rights you do not have is against the law. If you think it's not then I'm happy to sell you a licence to fish in the River Dee...
> it's not at all clear that it's against the law