obviously you can't change taxes on previous years, but these bonuses haven't been handed out. And if Congress changed the tax rate for this year, it doesn't apply only to the income after that date. And the lawyers can correct me, but whether there's a precedent for something or not doesn't make it challengeable.
government retroactively taxing previously earned income. Like going forward, they could tax at 90% (I'm assuming those execs already got this bonus money)