[jpc0]

> I suspect foreigners still have to register in the US before suing in the US

Generally that wouldn't be needed since it's no US copyright law that is being violated but the country of the copyright holder. Being in violation you would not be tried in the US but in the copyright holders country.

There is this whole thing where in general Copyright is unenforceable but when it matters it is enforced, since nobody really cares if you as an individual infringed on my Copyright since to be fair there just isn't enough to be claimed in damages for it not to be a frivolous suit.

But when the amounts become significant enough it is quite serious.

https://www.wipo.int/wipo_magazine/en/2006/02/article_0006.h... for reference to an influential case on copyright law, there are other more modern cases as well