A federal judge in Richmond, Va., ruled Monday that the Obama administration's health care reform law is unconstitutional.

The 42-page ruling by U.S. District Judge Henry Hudson is based on a key part of the law that requires Americans to buy health insurance.

"This court must conclude that…the minimum essential coverage provision exceeds the constitutional boundaries of congressional power," Hudson wrote.

"This case is not about health insurance, it is not about health care, it's about liberty," said Virginia Attorney General Ken Cuccinelli.

Cuccinelli filed the lawsuit just minutes after President Obama signed the controversial bill into law.

Starting in 2014, the law requires Americans to purchase health insurance or pay a fine.

Cuccinelli argues the federal government can't require Americans to buy insurance.

"No Congress before this one has tried to order Americans to buy a product because all the ones before this one knew they didn't have that power," Cuccinelli added. "It's an extraordinary expansion of federal power."

Hudson called the intentions of the federal government to improve the heatlh care system "laudible."

His ruling only applies to the individual mandate to buy insurance.

"Even the judge in this case ruled that the bill continues to move forward in terms of implementation, and obviously the individual responsibility aspects of this legislation weren't to go into effect until 2014," Press Secretary Robert Gibbs said. "So there's some time to work this through."

The White House said its confident the law is constitutional. The Department of Justice is expected to appeal the case.

"I would be shocked if it is not ultimately resolved in the Supreme Court," Cuccinelli said.

The state of Florida and 20 other states are part of a separate health care lawsuit.

A Florida judge will hear oral arguments in that case later this week.