A federal district judge Monday ruled a key provision of the Affordable Care Act unconstitutional, saying that the law’s requirement that most Americans purchase health insurance exceeds Congress’ authority. The ruling was made by Judge Henry Hudson, based in Richmond, who was appointed by President George W. Bush.

The Washington Post calls it the most significant legal setback for the Affordable Care Act.

Previously, two other district judges — in Detroit and Lynchburg, Va. — have upheld the reform law in separate court cases, notes an article in the New York Times.

Georgia has joined 19 other states in another lawsuit against the health care reform legislation. A major hearing in that case is set for later this week in Florida.

The constitutionality of the law, in all likelihood, will ultimately be settled by the U.S. Supreme Court.