When a special tribunal of the International Court of Justice charged Magneto with crimes against humanity in Uncanny X-Men #200, the scope of the legal proceedings hinged on the time Mutant Alpha reverted the master of magnetism from an adult to an infant (Defenders #16).
Prosecuting the case against Magneto was Sir James Jaspers, attorney-general of England. Leading the defense, Gabrielle Haller argued to strike all criminal counts that happened prior to that incident with Mutant Alpha.
- Gabrielle Haller: As I was saying -- at that time, Magneto was reduced to infancy, returned to a state of grace. His life can be said to have begun again. The man that was, at that moment, ceased to exist. In effect. he died. Which is, of course, the ultimate penalty for any crime.
- James Jaspers: Objection! This is the most preposterous perversion--!
Building her defense, Gabrielle Haller noted that Magneto was an adolescent during his internment at a Nazi concentration camp. Yet, decades later, medical testimony would now place the mutant criminal in his early 30s instead of his much older chronological age.
- James Jaspers: That's irrelevant! He committed those crimes, regardless of his age!
After a long deliberation, the court found in favor of the defense, restricting the indictment to those crimes committed after Magneto's "resurrection" (the court's term, not mine).
I, on the other hand, would have sided with the prosecution. For starters, Magneto did not die at the hands of Mutant Alpha. And once restored to physical prime through the actions of Eric the Red (X-Men #104), Magneto retained his full memories and mental faculties. His biological age may have altered back and forth, but he was the same person as before.