The U.S. Supreme Court will announce its highly-anticipated decision Thursday on the legality of the contentious health insurance reform law pushed by President Barack Obama.

The major focus of the nine-member court's ruling on the Affordable Care Act is the provision mandating that all Americans obtain health insurance by 2014 or face a financial penalty. Opponents say the provision is unconstitutional because the government is forcing people to buy a product they may not want, but the law's advocates say the individual mandate is necessary because it expands the number of people in the health insurance market.

The court, which is split between five conservative and four liberal justices, could decide to either strike down the individual mandate or the entire law. It could also rule that the entire law is constitutional and let it stand.

The law, which is aimed at providing coverage to more than 30 million uninsured Americans, is the signature domestic achievement of Mr. Obama's presidency. He defended the law and its various benefits during a campaign appearance in Miami earlier this week.

“I believe it is the right thing to do…I believe heath care reform was the right thing to do. I believe it was the right to make sure that over three million young people can stay on their parent's health insurance plan. I believe it was right to provide more discounts for seniors on their prescription drugs. I believe it was right to make sure that everybody in this country gets decent health care and is not bankrupt when they get sick.”

The president's likely Republican opponent in the November general election, Mitt Romney, pushed through a similar law during his tenure as governor of Massachusetts. But, Romney is firmly opposed to the new national law, which critics have dubbed “Obamacare,” and has vowed to repeal it if he is elected president.

“And, this is a decision by the way about whether or not Obamacare is constitutional. Whether it passes constitutional muster. And, so we're all waiting to see how the court will decide. One thing we already know however, we already know it's bad policy and it's gotta go.”

The Supreme Court will also rule on a part of the law that expands Medicaid, the joint federal-state health care program for low-income Americans and seniors.