At his confirmation hearing to become Chief Justice of the United States, John Roberts famously compared the role of a Supreme Court judge to that of a baseball umpire.
"It's my job to call balls and strikes," he said, "not to pitch or bat." As a disinterested referee, he would exercise restraint and defer to Congress, unless it passed a law that was clearly unconstitutional.
Tomorrow, the Supreme Court will announce whether or not it has struck down the Affordable Care Act (ACA) – known as Obamacare in the States – the signature legislation of President Barack Obama's first term. As well as the health insurance of 30 million people, the court's reputation for impartiality is on the line. In a series of 5-4 rulings issued by the conservative majority, with four liberal justices in dissent, the Roberts Court has shown a stunning disregard for precedent, in stark contrast with its leader's stated judicial philosophy.
"What's really at stake here is whether or not judges are bound by the text of the Constitution," says Ian Millhiser, Senior Constitutional Policy Analyst at the Centre for American Progress. "If they decide there is no longer a constraint on their discretion, there is nothing that judges cannot do. That strikes me as tremendously frightening."
In the seven years that Roberts has led the court, it has fulfilled one Republican campaign pledge after another. It has ruled that there is no limit to corporate spending in elections, that all handgun bans are unconstitutional and that there is no legal basis for affirmative action. It has curtailed the rights of consumers seeking to bring class action lawsuits and made discrimination claims more difficult to pursue.
Stephen Spaulding, Staff Counsel at liberal pressure group Common Cause, says Republicans, unlike Democrats, understand that the court is a partisan body: "I think that progressives have approached the court as a place of justice, whereas the right wing has approached the court as a place of pure power."
Naturally, conservatives do not see it that way. They believe the federal government has exceeded its constitutional authority and must be held in check.
"Roberts never said he wouldn't vote to overrule any precedents. If the precedents are wrong, then it's the court's job to overrule them," says Ilya Somin, Professor of Law at George Mason University. "You can call that activism if you like, but I think the court would be failing to do its duty if it didn't strike down unconstitutional laws."
The challenge to the ACA rests on an interpretation of Article 1, Section 8 of the Constitution: "Congress shall have power to regulate Commerce with foreign Nations, and among the several States, and with the Indian Tribes."
The most important precedent derives from a 1942 case, Wickard vs Filburn, in which the court ruled that the federal government had the right to impose wheat quotas. The Obama administration argues that as healthcare costs amount to 17.6% of the USA's Gross Domestic Product, the commerce clause grants power to regulate the industry.
Lawyer Paul Clement, who is leading the effort to overturn the ACA, has argued that the individual mandate requiring people to buy health insurance or pay a fine is an attempt to regulate inactivity. "It has very important implications for the constitutional principle of limited federal government power," says Somin. "If the government wins this case, there will be no limit to that power. If, on the other hand, the challengers win, then the idea that congressional powers are limited will be reinvigorated."
At oral argument, Justice Antonin Scalia, a conservative, suggested that if the mandate stands, the government will soon force people to eat their greens. "Everybody has to buy food sooner or later, so you define the market as food, therefore, everybody is in the market, therefore, you can make people buy broccoli," he said.
The comparison is a disingenuous one that originated on conservative talk radio: people who choose not to buy broccoli are not affecting its availability for people that want it, whereas healthy people waiting until they get sick to buy insurance drives up costs for those that need it.
In a recent New York Times poll, the court's approval rating fell to a historic low of 44%. Only one in eight respondents thought that judges reach their decisions based purely on the law – the majority of people have come to expect a politicised court. This is partly a result of Bush vs Gore, the decision to halt a recount in Florida, thus awarding the 2000 presidential election to the Republican party but in truth, the court has always been, to a greater or lesser degree, a partisan institution.
Progressives compare the Roberts Court to "the Lochner era" at the start of the 20th century. In Lochner vs New York, judges ruled that a law limiting the maximum working hours of bakers to 10 hours a day, six days a week violated "liberty of contract" – meaning that businesses could require their employees to work around the clock. The court consistently issued rulings friendly to corporations and hostile to unions, striking down numerous laws in the process.
In the late 1930s, the Hughes Court decimated the New Deal, invalidating several socially progressive, big government programmes, mostly in contentious 5-4 decisions. President Franklin D Roosevelt threatened to pack the court by appointing six new justices, but in "the switch in time that saved nine" Justice Owen Roberts changed sides and the government started to win the vital split decisions. "Even a blind man ought to see that the Court is in politics," Justice Felix Frankfurter wrote to Roosevelt, calling the change in outcomes "a lurid demonstration of the relation of men to the 'meaning' of the Constitution".
The most activist court of all – and the exception to the conservative rule – provided legal underpinning for the Great Society. A liberal majority led by Chief Justice Earl Warren ruled that segregation was unconstitutional, prohibited mandatory prayers at state schools and established a constitutional right to privacy. From 1962 to 1969, the court struck down 17 acts of Congress.
"Throughout the liberal academy you find the idea that the Warren Court overstepped and that you reap what you sow," says Dahlia Lithwick, contributing editor at Newsweek and Slate magazine. "By effecting an enormous amount of social change through the judicial branch and not through the legislative branches, it created the modern conservative movement."
Complaints about "legislating from the bench" have lost little of their appeal in Republican circles, even as a conservative Supreme Court pushes the boundaries of judicial activism. Former House speaker Newt Gingrich has suggested arresting judges that exceed their authority. "When it comes to dramatic rewriting of the Constitution, there's simply no comparison between the reality of the Warren court and even the grossest allegations made against the current court," says Ed Whelan, President of the Ethics and Public Policy Centre – a conservative think tank.
The Roberts Court has been uncommonly assertive. In Citizens United v Federal Election Commission, it transformed a narrow legal challenge – about whether a documentary critical of Hillary Clinton could be shown during election season – into a means to radically rewrite campaign finance laws. When President Obama used his State of the Union address to complain that the ruling would "open the floodgates for special interests – including foreign corporations – to spend without limit in our elections," cameras caught Justice Samuel Alito muttering "not true" under his breath.
At a recent press conference, Obama said he was confident the court would not strike down the ACA. "I'd just remind conservative commentators that for years what we've heard is the biggest problem on the bench was judicial activism or a lack of judicial restraint, that an unelected group of people would somehow overturn a duly constituted and passed law. Well, this is a good example," he said.
The health care law has already been defeated in the court of public opinion. More than $235 million has been spent on advertising attacking the reforms. In polls, around two-thirds of Americans say the mandate to buy insurance should be overturned. Justices could choose to let some parts of the law stand and strike down others, but without the revenue from compulsory enrolment it would be undermined.
Conflict of interest rules that would cause judges in lower courts to recuse themselves do not apply to the Supreme Court. Justice Elena Kagan was Solicitor General when the ACA was passed. Clement, the lawyer leading the challenge, clerked for Scalia and remains a friend. Justice Clarence Thomas's wife, Ginni, founded an organisation called Liberty Central, affiliated with the Tea Party, that views the health-care reform as an unconstitutional power grab. None of their votes are in doubt.
Justice Anthony Kennedy's vote is likely to be decisive. The split between four reliably conservative judges appointed by Republican presidents and four reliably liberal judges appointed by Democrats has placed power in his hands.
As Supreme Court judges are appointed for life, nominations to the court are an enduring presidential legacy. "If Mitt Romney wins the election and Justice Ruth Bader Ginsburg – two-time cancer survivor, aged 79 – were to leave the court, then I think you would have a watershed moment, where you would have a conservative president appointing her replacement," says Lithwick.
President George W Bush seated one third of the federal bench, meaning that at the level below the Supreme Court, there is a powerful bloc of conservative judges – and a glut of well-qualified, ideologically suitable replacements for Thomas and Scalia. Democratic efforts to replicate this have been thwarted by Republican obstruction of the confirmation process in Congress. Last week, Senate Minority Leader Mitch McConnell said he would block any judicial appointments for the remainder of Obama's term.
"Republican officials have understood for a long time that because judges serve for life and there's no mechanism to remove them, if you can get your people into the judiciary it gives you an ability to push politically unpopular agendas that would not pass in Congress," says Milhiser. "A key part of their policy is to capture the courts."
A few influential Republicans have urged the Supreme Court to exercise restraint, arguing that it cannot claim to be conservative if it continues to strike down laws. Federal Judge J. Harvie Wilkinson has written that the ACA should stand, even though he is opposed to the idea of government-run health care.
"There are conservatives who would say that it takes an enormous amount of hubris for nine judges to stride in and say 'this is how the country is going to be governed'," says Lithwick. "But there is an equally powerful, ascendant group who say 'we've got the keys to the car, let's go, go, go'." We will find out how far and how fast tomorrow.