Tax Control

The last few days Congress has been up in arms about AIG meeting its contractual obligations to current and former employees by paying bonuses. So Congress in its infinite wisdom has decided to tax those bonuses at 90%, because AIG (who put those bonuses into place before they were bailed out by the taxpayers) shouldn't be allowed to compensate its employees as it sees fit.

How long until Congress decides that the little people (i.e., anyone not an elected official or party member) should make no more than x, and taxes everything above x at confiscatory rates? That'd be fair, right?

More importantly, when did income taxes go from being a tool used to generate revenue for the government to a weapon of control and punishment?