What is the specific law or statute that says that people must file a tax return or pay federal income tax?

I understand the consequences that may occur, but I have never understood specifically what law has been broken.

26 USC 7201, 26 USC 7203, 26 USC 7206

Title 26 - Internal Revenue Code

http://www.law.cornell.edu/uscode/26

As long as their has been an income tax there have been tax protesters. Tax protesters make various claims on why the income tax doesn't apply to them. One of their many arguments is that there is no law making them liable.

So far, tax protesters have a perfect record in court. They have never won a case and gotten out of paying their taxes.

Pay your taxes and file your returns. You will be much happier in the long run.

Title 26 IRS code?