While the media obsesses over Donald Trump's taxes, principled libertarians like former Rep. Ron Paul (Tex.) says the real problem is that the federal government believes it has a right to what someone earns.

Paul appeared on Fox Business on Monday to discuss the nature of income tax.

"The real unconstitutionality of the tax code and the income tax is the way they collect it," Paul said. "It assumes you're guilty until proven innocent and that turns the constitution on it's head."

Repealing the income tax was a position that Paul often championed both in Congress and during his three runs for the White House. He even mocked Mitt Romney for saying that half of America didn't pay taxes.

"We're half way there because really if you're living in a free society, the founders didn't intend it, if you had the proper size government, there would be no income (tax)," Paul continued.

Liberals often make the argument that tax cuts have to paid for but Paul refuted that idea. He claimed that it presupposes that the government owns you and owns 100 percent of what you earn and allows you to keep part of it as long as you "obey the rules and fill out the forms."

"In a free society, you should own all the fruits of your labor and the whole country would be better off," Paul said.

Watch the whole interview below: