The GQ picture was not in the public domain, it had to be purchased as it was copy written and it appears that it was, by Cruz’s campaign manager, and then given to the superPAC to use in the ad.
That is why Trump keeps saying that Cruz knew all about the use of the picture.
I have no problem with Cruz being part of the plot to use the picture. That’s not the point. The point is that it is not a big game issue. It’s hunting rabbits.
“Public domain” has a legal definition regarding use of copyrighted material, but it also has the sense of ‘being out there already for everyone to see.’
Those pictures were not secret. They were public.