The U.S. Supreme Court meets Friday to take its first vote on whether to strike down one of the most important pieces of social and economic legislation passed by Congress in the past half century — the Affordable Care Act. If there are enough votes in the court's closed-door conference to reject all or part of the law, all of the votes will likely have come from the five Republican appointees acting over the objections of their Democratically appointed colleagues who seemed in questioning to support the law's constitutionality.

In a way, it would be a fitting end for the Affordable Care Act, which passed by the narrowest and most partisan of majorities in Congress.

But a 5-4 partisan divide could damage the court's credibility, opening it to criticism that it is acting like just another political branch of government rather than as a neutral interpreter of the law.  Concern about that institutional damage could prompt Chief Justice John G. Roberts Jr. or Justice Anthony Kennedy to uphold the law.

"This (law) was a major issue of the 2008 campaign and of this campaign," Joel K. Goldstein of Saint Louis University Law School writes in an email. "When is the last time the court has overturned such significant legislation, which was so closely identified with a president while he was in office? Even a decision that embraces existing (legal) doctrine but overturns the individual mandate will be a big deal."

Goldstein continues: "Moreover, a decision narrowly overturning the mandate is likely to be the product of a 5-4 vote with the five 'conservative' justices appointed by Presidents (Ronald) Reagan, (George H.W.) Bush and (George W.) Bush opposed by the four appointed by Presidents Bill Clinton and Barack Obama. Such a result would reinforce the view of a political court which Bush vs. Gore and Citizens United encouraged."

Bush vs. Gore resolved the 2000 presidential election and Citizens United in 2010 opened election campaigns to unlimited corporate contributions.

A conservative court striking down a Democratic president's signature piece of  legislation also would harken back to the early years of the New Deal when a 5-4 court struck down major elements of President Franklin Roosevelt's agenda, only to retreat after Roosevelt threatened to pack the court.

More broadly, the extraordinary six hours of argument this week on Obama's signature accomplishment echoed more than two centuries of conflict over the power of the federal government in relation to the states and to individuals -- conflicts that included fights over the Bank of the United States, slavery, wage and hour laws, and civil rights laws.

One case discussed by the justices was the two-century old McCulloch vs. Maryland decision in which Chief Justice John Marshall upheld the Bank of the United States -- hated in its day as much as "Obamacare" is today.  In that decision, Marshall decided that the Congress had broad power to accomplish those things necessary and proper to its ends. Marshall also predicted, correctly, the many battles in the future over the division of power between the federal government and the states.

Political risk

Michael A. Wolff, former chief justice of the Missouri Supreme Court and a Saint Louis University law professor, writes in an email that the justices could face a political backlash with a 5-4 decision striking down the law.

"The justices should fear what they do not know — electoral politics," says Wolff. "What they do not know is whether there would be a political reaction to their activism if they strike down the law that would help Obama's re-election. That result would determine the kind of persons appointed to the court. The problem is that some of them think they know something about electoral politics, though not one of them ever has run for dog catcher (to paraphrase Sam Rayburn)."

But other legal experts think a decision throwing out parts of the law would be neither as monumental nor as risky.

Alan Howard, a law professor at Saint Louis University Law School, predicts that a decision against the law would be written narrowly to avoid knocking down existing precedents on federal authority. The court could say that Congress did not have the power to create the individual mandate to purchase health insurance, while still recognizing Congress has the broad commerce power to justify important legislation like the Civil Rights Act.

"If the court strikes down the individual mandate," Howard writes in an email, "it will do by writing a narrow opinion that distinguishes the mandate from anything Congress did in any previous federal law that the court upheld. Thus I don't think that if the court strikes down the mandate that any prior federal law the court upheld under the commerce clause is now at risk of being struck down by the court in the future....Thus striking down the individual mandate — drum roll — will not represent a sea change in the court's commerce clause jurisprudence.”

Bruce La Pierre, a Washington University law professor, says that the "invalidation of the ACA would be a sad chapter, an unnecessary chapter in the book of federalism," but he agrees with Howard that the court’s decision would likely be narrow and have little lasting constitutional impact.

Twice during the Rehnquist court, the Supreme Court ruled that Congress had exceeded its commerce powers: the Gun Free Safe Schools Act and the Violence Against Women Act. But neither decision turned out to be a major reduction in congressional power.

"Invalidation of ACA will have as little lasting significance" as those two decisions, wrote La Pierre in an email.  "These two decisions, which narrowed the reach of the commerce power over individuals, were little more than two shots across Congress’ bow: 'warning don’t go too far.'

"So when political liberals lash out at the Roberts court for its judicial activism (which it would be) in holding the ACA unconstitutional and forget their own private delight when judicial activism serves their interests... we should ignore their claims that the world as we know it is coming to an end.”

Judicial activism?

Dave Roland, director of litigation for the libertarian Freedom Center of Missouri, agrees with La Pierre that "the Supreme Court's previous flirtations with imposing such limits have been short-lived.  If the court does not use this opportunity to throw up a barrier to congressional power, it is unlikely the justices will do so in the foreseeable future," he added in an email.

"But if a majority of the justices do rule the mandate unconstitutional, the court's future course will likely be determined by the presidential election in November. The winner of the election will almost certainly appoint Justice (Ruth Bader) Ginsburg's successor and perhaps will appoint successors for Justices (Antonin) Scalia, (Anthony M.) Kennedy, or (Clarence) Thomas. If Obama makes those appointments, one could safely assume that the court will swiftly repudiate (or simply ignore) whatever principle the court might employ to strike down the mandate.”

Like La Pierre, Roland says that liberals' complaints about activism by the court is hypocritical. "My deep concern is that the past few decades' bipartisan hue and cry over 'judicial activism' has generated a perverse sort of consensus that judges should not treat the Constitution as a functioning restraint on the will of the majority."

Roland argues, "But in fact Americans adopted constitutional systems of government to ensure that there are limits on the powers that their governments may exercise. Just as judges have the authority to strike down laws that violate freedoms preserved in the Bill of Rights, they also have the authority (and I would argue an affirmative obligation) to invalidate laws that exceed the limited powers the people granted Congress through the Constitution."

Roger Goldman, of Saint Louis University Law School, notes, however, that Kennedy, the swing justice, has not been reluctant in the past to second-guess Congress.

Leave it to democratic process

La Pierre says the health-care law is one where it is particularly inappropriate for the court to substitute its judgment for the political branch. "The political process...has never been a better alternative to judicial review than in this case," he wrote. "If it is a really bad law — an abuse of the commerce power — then do what John Marshall said: use the democratic process to repeal the ACA."

Wednesday's argument over severability — what parts of the law, if any, can stand if the individual mandate falls — underscored how involved in legislating the court could become if it voided part of the law. Scalia joked that it would be cruel and unusual punishment to force him to read all 2,700 pages of the law and figure out which parts could survive and which couldn't. (The comment has drawn criticism from some who think justices should read the law before throwing it out.)

Scalia and other justices suggested that striking down the whole law might be the least activist and most deferential way to go because it would leave to Congress the decision about what parts of the law to revive. The political reality, however, is that the current, gridlocked Congress would be hard-pressed to pass a fix.

Scenario to uphold

Even though the five conservatives on the court frequently sounded as if they wanted to strike down all or parts of the law, most legal experts agree that it quite possible — maybe even probable — that Roberts and Kennedy will join the four liberals to uphold it 6-3.

Roberts has to be concerned about the legitimacy of the court and his reputation. From the time of his confirmation hearings, he has spoken about the importance of finding greater consensus on the court. To follow up the divisive 5-4 decision in Citizens United with another divisive 5-4 decision along perceived party lines could hurt both the court's reputation and his own.

Roberts would have another incentive to uphold the law: He can assign himself the opinion and make sure that it is extremely narrow, approving this exercise of power but nothing beyond.

These institutional prerogatives might not be strong enough, however, to cause Kennedy or Roberts to abandon what appeared to be their serious questions about the law. Kennedy clearly is concerned that the individual mandate reorders the relationship between the government and the individual in a way that could jeopardize liberty. And he is concerned that the expansion of Medicaid damages federalism by confusing people whether they should blame the federal government or the states for their health care.

For Kennedy, liberty, accountability and federalism are important concerns.

Howard points to one other fact that could keep a 5-4 decision against the law from damaging the court. "As a political matter," he writes, "no doubt were the court to strike down the entire law, it would rate a banner headline on the front page of most if not all papers simply because the court had struck down the Obama's administration's 'most important legislative achievement' to date. It would be a bigger deal if the health-care law passed with overwhelming majorities in both houses and if polls showed that the overwhelming majority of the citizenry loved the law. But the law passed largely along party lines and most polls show that the majority of the public does not love the law."