The limit to federal crimes is pretty firm and based on a plain reading of the Constitution.
“he shall have Power to grant Reprieves and Pardons for Offenses against the United States”
Which means federal law in pretty much our entire legal system. It’s one of the few hard and fast things about Presidential pardons. But like anything in the law you could challenge that in the court. You could try to pardon a state offense and either hope the state in question doesn’t challenge it, or argue when they do that Presidential pardons cover state offenses.
But there’s very little chance that’ll fly. Manafort is likely to be charged in states that aren’t Trump friendly and have no interest in pardoning him. That’s the whole idea with planning to charge there. And there isn’t really a court that’s likely to accept any arguement for expanding the presidential pardon to cover state offenses. It would over turn one of the longest standing Constitutional traditions , one that’s less based on interpretation than plain text. And conservative judges are famously protective of state’s rights, even the Trump judges.
They also killed Litvinenko in the UK. And there have been plenty of others killed or disappeared outside Russia. But thus far Putin’s government seems to have avoided killing citizens of other countries on foreign soil.
So I dunno how realistic those fears are. Especially since Manafort is in a US jail right now. And likely to stay there.
