Lawsuit Challenges Constitutionality of Obamacare Tax

The Supreme Court said it's a tax, but tax bills must come from the House

"Obamacare" looks increasingly inevitable, but one lawsuit making its way through the court system could pull the plug on the sweeping federal health care law.

A challenge filed by the Pacific Legal Foundation contends that the Affordable Care Act is unconstitutional because the bill originated in the Senate, not the House. Under the Origination Clause of the Constitution, all bills raising revenue must begin in the House.

The Supreme Court upheld most provisions of the act in June, but Chief Justice John G. Roberts Jr. took pains in the majority opinion to define Obamacare as a federal tax, not a mandate. That was when the Sacramento, Calif.-based foundation's attorneys had their "aha" moment.