The U.S. Justice Department has asked the Supreme Court to uphold the Obama administration’s historic overhaul of the nation’s health care system.

The Justice Department on Wednesday filed an appeal asking the nation’s top court to review an earlier decision by a federal court, which ruled the legislation exceeded its authority by requiring most Americans to pay for health insurance or face a penalty.

The court ruling, issued in August, upheld the rest of the health care reforms as legal.

Earlier Wednesday, 26 U.S. states and an organization representing small businesses filed appeals to the same ruling, asking Supreme Court justices to declare the entire law unconstitutional.

Three federal courts have so far issued conflicting decisions on the health care legislation, with one upholding it, another partially striking it down, and a third declining to issue an immediate ruling.

Legal experts say the Supreme Court is likely to rule on the issue by the end of its current session in June, which would fall in the middle of the 2012 presidential campaign.

The health care debate has been divisive in American politics, with many Republican presidential candidates promising to repeal the law, if elected.