The Supreme Court on Monday joins the nation’s vitriolic debate over the landmark health-care law and the limits of federal power. And though thousands of pages of legal arguments about the Constitution’s history and the court’s precedents have landed on justices’ desks, the outcome may also hinge on less tangible factors.

Public opinion. The nation’s volatile political climate. The court’s self-consciousness about its own partisan divide. And the pivotal role it plays in deciding the nation’s thorniest social issues.

Experts say all of those go into the mix as justices consider the extraordinary step of striking down — for the first time since the New Deal — a monumental domestic program proposed by the president and passed by Congress.

The three days of arguments that begin Monday are the inevitable result of a legal battle that began the moment the Patient Protection and Affordable Care Act became law two years ago. And the court’s conclusion will land in the summer heat of a presidential campaign in which each of President Obama’s Republican challengers have made opposition to the law an unshakable pledge.

Such a charged political atmosphere is not the court’s favored environment. The justices are protective of their charge as neutral arbiters of the law, what Chief Justice John G. Roberts Jr. described as umpires calling balls and strikes.

But some see other factors at work in the court’s decisions — and they say there should be nothing surprising or even particularly negative about that.

“You don’t have to view them as junior varsity politicians to see that their political views and economic predilections have some influence on what they do,” said Jeff Shesol, whose most recent book chronicled the New Deal battles between the Supreme Court and President Franklin D. Roosevelt.

Certainly the presidents who appointed the nine justices — Ronald Reagan, George H.W. Bush, Bill Clinton, George W. Bush and Obama — took ideology into consideration in making their selections.

Three days of arguments

Roberts and the court have gone to some lengths to show the nation the seriousness and evenhandedness of their inquiry.

They have scheduled six hours of arguments over three days, the most in 45 years. They will examine the law in detail, even parts that no judges below them have found constitutionally questionable. And while cameras are still forbidden, the court has changed its rules to release audiotape and transcripts of the arguments each day.

Roberts even made something of a preemptive strike this year when he defended his colleagues against criticism that some come to the arguments with agendas.

“We are all deeply committed to the common interest in preserving the court’s vital role as an impartial tribunal governed by the rule of law,” Roberts wrote in his annual report on the state of the judiciary.

But the case sets up a classic problem for the court: when to defer to the political branches as the elected representatives of the people and when to blow the whistle when those politicians have intruded on the Constitution’s protection of the people.

The Obama administration points to the arc of decisions stretching back to the New Deal in which the court has said the Commerce Clause and other constitutional provisions provide Congress authority to deal with national economic problems.

The uninsured consumed about $116 billion in health-care services in 2008, Solicitor General Donald B. Verrilli Jr. told the court in the government’s brief. The amount was absorbed by providers or passed along to others in increased health insurance premiums, about $1,000 a year per family.

“Because health insurance is the principal mechanism for meeting these unpredictable and often expensive liabilities, it was reasonable for Congress to invoke that same mechanism to address the problem of uncompensated care,” Verrilli wrote.

Paul D. Clement, representing Republican officials in 26 states who have challenged the law, warns the court that the mandate “rests on a claim of federal powers that is both unprecedented and unbounded.”

Only by “checking” the government now, he wrote, can the court make clear that this “uncabined authority is not among the limited and enumerated powers granted the federal government.”

Public opinion

A Washington Post-ABC News poll showed that two-thirds of respondents want the court to invalidate the entire law or the mandate that all individuals purchase health insurance by 2014.

But those who have chronicled how public opinion affects the court said such immediate concerns have little impact on the justices.

“I hope the justices aren’t sitting around reading public opinion polls,” said Barry Friedman, a New York University law professor and author of “The Will of the People: How Public Opinion Has Influenced the Supreme Court and Shaped the Meaning of the Constitution.” “Something has gone seriously off the rails if that is true.”

The court has shown it is unafraid to buck public opinion to protect constitutional principles, particularly in free-speech cases. But Friedman says the court eventually aligns itself with public opinion on controversial issues, such as civil rights and gun ownership.

Shesol, the author of the Roosevelt book “Supreme Power,” said there are obvious parallels to the Supreme Court’s consideration of the progressive New Deal legislation.

Both concern the scope of federal authority and how “the national government is empowered to deal with national problems,” he said.

But the stakes were considerably higher in Roosevelt’s time, and public opinion shifted overwhelmingly to endorse the necessity of the New Deal programs, Shesol said. The string of Roosevelt’s programs reviewed by the court gave the justices a way to adjust to that new reality.

‘Freedom’ for court

Lee Epstein, a political scientist and lecturer at the University of Southern California Gould School of Law who studies public opinion and the court, says the case will not have lasting impact on the court’s reputation no matter the outcome.

“I think it’s one of those cases where they have the freedom to do what they want,” she said.

But she noted the court’s partisan divide, which fits neatly into its usual ideological lineup. Roberts and Justices Antonin Scalia, Anthony M. Kennedy, Clarence Thomas and Samuel A. Alito Jr. were appointed by Republican presidents, Justices Ruth Bader Ginsburg, Stephen G. Breyer, Sonia Sotomayor and Elena Kagan by Democrats.

Since those appointed by Democrats seem likely to uphold a broad reading of government’s powers, a 5 to 4 decision would highlight the partisan divide.

When Epstein considers the court and reads the arguments in the case, she said she sees a conflict between the justices’ personal ideologies and what the court’s precedents seem to forecast.

“The political-scientist side of me sees it 5 to 4” to strike the law, she said. “The law professor side of me sees it 6 to 3 to uphold.”

Somewhat presciently, as Washington lawyer Adam J. White noted recently in the Weekly Standard, Obama talked as a senator about how Supreme Court justices might decide difficult cases.

He set as examples cases where “the constitutional text will not be directly on point” and cases looking at “whether the Commerce Clause empowers Congress to speak on those issues of broad national concern that may be only tangentially related to what is easily defined as interstate commerce.”

In such tough cases, he said, “the critical ingredient is supplied by what is in the judge’s heart.”

Unfortunately for Obama, as his signature domestic achievement goes before the Supreme Court, that missing ingredient was the reason he gave for voting against the confirmation of Roberts.