Is the US's IRS Collecting Income Tax Legal?

Related: The Money Masters

And a quote from the president who was sucker enough to create The Federal Reserve:

I am a most unhappy man. I have unwittingly ruined my country. A great industrial nation is controlled by its system of credit. Our system of credit is concentrated. The growth of the nation, therefore, and all our activities are in the hands of a few men. We have come to be one of the worst ruled, one of the most completely controlled and dominated governments in the civilized world - no longer a government by free opinion, no longer a government by conviction and the vote of the majority, but a government by the opinion and duress of a small group of dominant men. - Woodrow Wilson