The individual mandate portion of the Obama health law, which would require Americans to purchase a minimum level of health insurance starting in 2014, suffered another legal defeat Tuesday as a federal judge in Pennsylvania struck down the plan - and added another new voice to the legal battle.

"The power to regulate interstate commerce does not subsume the power to dictate a lifetime financial commitment to health insurance coverage," wrote Judge Christopher Conner.

It was a victory for critics of the Obama health law, bringing another case in a different judicial circuit into play, as this issue moves inexorably towards the U.S. Supreme Court.

"Based upon careful review of Commerce Clause jurisprudence, the court declares the individual mandate to be an unconstitutional extension of authority granted to the federal government," ruled Judge Conner.

This case would go next to the Third Circuit Court of Appeals in Philadelphia, which has yet to weigh in on the Obama health law.

So far, three appellate courts have taken up the issue, with each one coming to a different conclusion: