> Why would any other country handicap themselves by joining such an obviously corrupt court that judges them but not the US?

It's not a corrupt court. It has judged crimes against humanity cases before, and a lot of countries give credence to it.

https://en.wikipedia.org/wiki/List_of_people_indicted_in_the... the people in this list all deserve to be there, I can't see a single exception

My own country (Brazil) supported South Africa charges of genocide against Israel because we believe in this court and the role it fulfills.

For me, the sole problem with this court is that it's reluctant to judge American war crimes and crimes against humanity. But as Europe leaves the US sphere of influence, maybe they will grow a spine. It would be unfortunate if people like George W Bush, Dick Cheney, John Choon Yoo and Jay Scott Bybee died before they were indicted by this court.