Updated at 4:32 p.m. Eastern.
A Virginia federal judge on Monday ruled that the individual mandate - a major precept of the Obama administration's healthcare legislation - exceeds the constitutional boundaries of congressional power.
"On careful review, this Court must conclude that Section 1501 of the Patient Protection and Affordable Care Act - specifically the Minimum Essential Coverage Provision - exceeds the constitutional boundaries of congressional power," wrote U.S. District Court Judge Henry E. Hudson.
"At its core, this dispute is not simply about regulating the business of insurance - or crafting a scheme of universal health insurance coverage, - it's about an individual's right to choose to participate," he wrote.
Hudson did not grant petitioners' request for an immediate injunction against the entire law, only on the portion regarding the individual mandate, the requirement that individuals purchase health insurance or pay a penalty.
One consumer group, Health Care for America Now, said it was "pleased that Hudson rejected Virginia Attorney General Ken Cuccinelli's attempt to strike down" the entire Act, but disagreed with Hudson's view that the individual mandate requirement is unconstitutional.
"We think that is wrong on the merits and bad for people's health. If his decision is upheld, it would give the green light for insurance companies to deny people care based on pre-existing conditions," said HCAN spokesman Avram Goldstein in a statement.
Four other federal district courts of equal rank "have determined that the law is constitutional or have dismissed complaints on procedural grounds, and the ultimate decision will rest with the U.S. Supreme Court," Goldstein added.
More than 20 states have filed lawsuits challenging the Act, which may ultimately be decided the Supreme Court.