The administration's move puts an end to months of speculation about its strategy in the case. Now both sides want the Supreme Court to deliver a speedy decision, one that could affect President Barack Obama's re-election prospects.
Mr. Obama has described the law he signed in March 2010 as one of his top achievements, but it has drawn, at best, mixed results in opinion polls, and all of his potential Republican rivals have pledged to repeal it. If the Supreme Court rules by June 2012, as now appears likely, it would put health care back in the spotlight as the parties gear up for their conventions.
Some Republicans said that might help their cause, regardless of how the Supreme Court decides.
Having this particular issue emerge right in the middle of the presidential campaign draws attention back to the fact that, while the economy was tanking, he was focusing on health care," said David Winston, a Republican pollster.
The White House said it expects to be vindicated at the Supreme Court, and compared the law to landmarks such as the Civil Rights Act that survived constitutional challenges and won widespread popular acceptance.
"We know the Affordable Care Act is constitutional. We are confident the Supreme Court will agree," said White House adviser Stephanie Cutter.
While the likely mid-campaign timing of the decision may not be ideal for the White House, any attempt to push the ruling back into 2013 would have been risky, too. Opponents of the law were already calling for a quick Supreme Court ruling, so a slow-walking strategy would have made the administration look less confident—and the Supreme Court might have chosen to take the case quickly anyway.
A decision before the 2012 presidential election also would foreclose any possibility of a Republican president declining to defend the health-care law in court.
Democrats familiar with White House thinking said Wednesday that officials concluded this case was likely to wind up before the high court in 2012 regardless, and that delaying it could push the proceedings even closer to Election Day.
They want to get a decision as removed from the heat of politics as possible," said one person close to the White House.
This person said that while the White House is confident of winning, it is preparing for the possibility that the Supreme Court could strike down parts of the law and leave other parts intact. In that case, the Obama administration would have control over how the surviving parts are implemented.
So far, two of three federal appeals courts ruling on the law have found in the administration's favor. A third, the 11th Circuit Court in Atlanta, ruled that the law's "individual mandate"—the requirement for most Americans to carry health insurance or pay a penalty—was unconstitutional, but said the rest of the law could stand. A fourth court, in the District of Columbia, heard arguments this month.
In Wednesday's filings to the Supreme Court, both sides appealed the 11th Circuit's ruling. The Obama administration asked the high court to uphold the individual mandate along with the rest of the law, while the law's opponents said the whole law, not just the mandate, should be struck down.
The two sides agreed on one point, saying a speedy decision is desirable.
"Until this court decides the extent to which the [law] survives, the entire nation will remain mired in doubt, which imposes an enormous drag on the economy," said the National Federation of Independent Business, one of the plaintiffs in the 11th Circuit case.
"It's important to get a decision sooner rather than later," said an official at the Justice Department, which filed its appeal more than a month before it was due. An early ruling would allow the federal government to "get on with the business of implementing the law," while allowing states, businesses and individuals time to plan, the official said.
The Supreme Court isn't required to hear the case, but the request by both sides for a ruling, as well as the divided opinions by lower courts, will likely impel it to take the case in its current term, lawyers said.
Many of the law's provisions, including state-based exchanges where consumers could comparison-shop for coverage, are scheduled to take effect in 2014.
Mr. Obama's supporters hope the Supreme Court will vindicate the law, giving the president a major boost heading into the fall campaign. But that could also help energize Republicans, because the only way to overturn the law at that point would be to elect a Republican president and Congress to repeal it.
Republican pollster Bill McInturff, who co-directs the Wall Street Journal/NBC poll with Democrat Peter Hart, said any attention paid to health care is risky for Mr. Obama, particularly because those strongly opposed to the law outnumber those strongly in favor. "The public discussion has not yet ever gone well for the president or the Democrats," Mr. McInturff said.
Neera Tanden of the Center for American Progress, who worked on health care early in the Obama administration, said the campaign is more likely to focus on the economy than health care, particularly if former Massachusetts Gov. Mitt Romney, who championed the Massachusetts health law that was a model for the Obama version, is the Republican candidate. "Republicans don't want to talk about this," she said. "If they did, they would be talking about it every day."
The 11th Circuit case is the largest challenge and is led by Republican attorneys general and governors in 26 states. Challengers assert that the Affordable Care Act exceeds Congress's power to regulate interstate commerce by compelling individuals to undertake a commercial activity—purchasing health coverage—or pay a penalty.
The Justice Department's brief relies heavily on an opinion by a conservative judge, Jeffrey Sutton of the Sixth Circuit Court of Appeals in Cincinnati, who earlier this year wrote a concurring opinion upholding the insurance mandate as a reasonable way for Congress to exercise its authority over the insurance and health-care markets.