Magneto is to be tried by an ad-hoc international criminal court akin to the Nuremburg trials. (I suppose the United States wasn't willing to hand him over directly the Soviet Union? Sadly, the claim that it is the first court of its kind would no longer hold up, because it has been necessary to set up special ad hoc international criminal tribunals for Rwanda, the former Yugoslavia and eventually a standing International Criminal Court was established. Americans: you really should get around to joining that one of these years, it's making you look ridiculous.)
Our impromptu tribunal is in Paris, rather than the Hague, presumably as reference images of the City of Light are a tad easier to come by.
For the prosecution, we have Sir James Jaspers, Attorney General of England and Wales. This is slightly weird - Attorney General doesn't have the same hands-on role in prosecutions as they do in the United States (that department is headed by the Director of Public Prosecutions), but it's at least true that he represents the British government at the ICJ, so we'll give it a pass.
More worrying is Magneto's defence team, which is the Ambassador of Israel to the United Kingdom, Gaby Haller, and Charles Xavier. Now, let's accept that Haller and Xavier have perfectly good in-story reasons for supporting Magneto right now. Nonetheless, what on Earth are they thinking. Were they not able to find an actual legal team? Does Xavier really want to be known in public not only as a "mutant-lover", but also as an actual Magneto apologist?
And worse than that: what is the Israeli government thinking? Is Haller acting in an official capacity? If they wanted to do an Israel-offers-mutants-asylum storyline, that would be pretty interesting, but that's really not what's going on, and instead it seems like Haller is going rogue. She gotta end up being sacked as a result of this, right?
To the the trial itself. Our first bit of business is the stuff prior to X-Men #104. The defence argues that that was a different Magneto, and that the current one can only be held responsible for actions after he has been restored to adulthood. Which might be true, but the court just accepts this assertion without questioning how it can be proven. The defence asserts that it's an established fact that Magneto went to Auschwitz, must therefore be in his 60s, and has clearly been de-aged since, and this all means he shouldn't be put on trial for stuff before he got turned into a baby. No evidence is presented of this remarkable claim. I don't know how this works - maybe they got Johnnie Cochran to give them pre-trial coaching? - but it does, and so the trial is confined mostly to the destruction of the Soviet ship Leningrad and the city of Varykino.
Magneto gladly 'fesses up to both of these, but doesn't see the problem. The Leningrad had just tried to nuke him, after all, and he destroyed the city in a relatively nice way.
Meanwhile, back at the mansion, tumbleweed sits down and starts singing about gold.
The X-Men and New Mutants are in Paris for this excitement, having been 'ported there by Loki following the shenanigans of New Mutants Special Edition #1/X-Men Annual #8. There are anti-mutant demonstrations and, very worryingly, someone is framing the X-Men for a series of terrorist attacks. But there's hope, too: the largest demonstration Paris has ever seen, in some kind of solidarity with our mutants. Maybe some of them say "Magneto avait raison"?
During all this, Xavier has been getting weaker and weaker. He's totally unprepared for the moment when the Strucker twins - the ones who had gone after Storm in Africa arrive, and become Fenris by touching their skin together. They are the children of the Strucker seen in the flashback in #162, and they want their revenge. There is fighting. Magneto stops Jaspers from killing one of the Struckers after they've been separated, which gets him points with the judge. More scuffling, and Xavier is injured beyond any normal human healing, but is fished out by the Starjammers using a stargate, for Sirpinksi to heal. Xavier's parting wish is for Magneto to take over the school and the X-Men, although he doesn't do so within earshot of anyone other than Magneto himself, which will lead to complications.
The trial is left in ruins. The defendant absconds, although since he's very shortly to be found at his defence attorney's country mansion running his school for gifted youngsters, it should hardly be a problem to track him down. And maybe he was about to be acquitted anyway?
And that's the first two hundred issues of X-Men. There have been line-up changes, there have been fake-outs. But never before has it done anything like this - sending Xavier away and having their former archenemy in charge. This is gonna be fun.