This is an older supreme court case (90s/2000s I think) but my recollection is that you've got it totally backwards--the decision turned on whether or not there

This is an older supreme court case (90s/2000s I think) but my recollection is that you've got it totally backwards--the decision turned on whether or not there is a real victim. Their reasoning was that videos of real kids create a market for the exploitation of real kids, which is a harm that overcomes first amendment protections, whereas depictions need not (their reasoning, not mine). I don't believe verisimilitude was even addressed. Now, if you mean a depiction's similarity to a particular, real child, I'm not sure how that would play out (or if it was addressed in the decision).