Is there a law which requires private citizens to pay federal income tax?

I have been hearing that there is no actual law to this effect.
Could this be true? Please cite the specific laws and supreme court rulings which are relevant, if you can.

An 11 part documentary asking the same question:
http://www.youtube.com/watch?v=3ueEfRXZCVA
Update: Thank you all for your help in exposing this lie. With a little research I found: TITLE 26 > Subtitle F > CHAPTER 61 > Subchapter A > PART II > Subpart B > § 6012, and it cleadly is law. I also read every single court case described in the documentary, and only one was accurataely described, and... show more Thank you all for your help in exposing this lie. With a little research I found: TITLE 26 > Subtitle F > CHAPTER 61 > Subchapter A > PART II > Subpart B > § 6012, and it cleadly is law. I also read every single court case described in the documentary, and only one was accurataely described, and even that one was poorly interperetited. This has only taken me 4 hours or so to debunk.
8 answers 8