Getting the rights to publish images of Superman in my recent article was far more complicated than I had expected, so I wrote a blog post about it at the UofT Press blog.
I would just want to add, as an addendum to the post, that DC Comics granted me the rights to publish two of the four images requested, but did not elaborate on the reasons. The two they granted explicitly mentioned the Jewish judge Samson and were the two that had Superman in costume, so I would speculate that they were approved for some combination of those reasons, but who knows?