A summary can't be a matter of copyright. It's probably just the vehicle HBO chose to be able to identify the leaker, because claiming copyright infringement these days is like a superpower, and then use different hammer to go after them.

This is a legally tricky minefield. Depending on what is in summary, it -may- be subject to copyright but be protected as fair use... but a work being unpublished weighs against (but does not preclude) free use.

I could see an argument that it is a trade secret, too-- which could be used to oppose downstream dissemination.

I think it'd pretty much have to be a script, a screenshot, audio, or video to qualify as copyright infringement. I can tell you what a song is about without risk of violating copyright, but the moment I start quoting lyrics things get riskier.

I think it depends on the depth of the summary, and the purpose. You can do quite an indepth analysis as part of educational material for example, which is one of the tests of fair use.

I think a key thing to remember when assessing your own liability is fair use is a defense, not an automatic guaranteed right for blanket uses.

Leaking spoilers of unpublished works can definitely cause market harm, and serves no wider good for the market the same way educational material would.

I wouldn't like to be on the receiving side of this lawsuit. At the very least it's going to be expensive to defend against.

That's the rub. When it comes to copyright, money makes right. The one with more money and willingness to go to court will win. Not who is actually legally right.

That's not just copyright, it's our entire legal system. A corporation can intentionally murder hundreds of thousands of people and get nothing but a slap on the wrist fine.

That too makes sense.