SPRINGFIELD — To one side, it was “the most massive fraud in American history.” To the other, the Illinois Supreme Court should not become the first court to overrule itself based on a federal agency’s amicus brief.

Those were the characterizations lobbed across the courtroom by lawyers in the long-running, multibillion-dollar lawsuit against tobacco giant Philip Morris that returned to the Supreme Court Tuesday morning after a decade of legal-system wrangling.

For roughly 50 minutes, the state’s top justices heard lawyers for the company argue the court’s original decision to toss a $10.1 billion verdict was the right one.

An attorney for the plaintiffs, meanwhile, argued an appellate court was correct to reinstate the litigation last year on the basis of new evidence.

The original claim was that the company violated the Consumer Fraud Act, tricking consumers into purchasing cigarettes by using terms such as “light” and “low tar” to make them seem safer.

The high court overturned the verdict in 2005, saying the Federal Trade Commission had authorized the descriptors through consent decrees in 1971 and 1995.

But the FTC said in a friend-of-the-court brief in a separate case in 2008 — as well as a subsequent memo known as a “rescission of guidance” — that it had “neither defined those terms, nor provided guidance or authorization as to the use of descriptors.”

The plaintiffs, a class of more than 1 million cigarette-buyers between 1971 and 2001, used those claims to file a Section 2-1401 petition for relief from the high court’s 2005 judgment, saying the case would’ve turned out differently with that evidence.

Madison County Circuit Judge Dennis R. Ruth ruled in 2012 that the new evidence undercut the high court’s ruling to an extent, but the plaintiffs still didn’t prove that the state’s top judges would have ruled differently.

Last year, the 5th District Appellate Court disagreed in a 29-page decision authored by Justice Melissa A. Chapman.

The Supreme Court agreed to hear the case again last September.

The company argued the 2008 claims didn’t amount to new facts — rather, the FTC was merely making new legal interpretations. If that counted as new evidence, then the finality of judgments is perpetually at risk, the company lawyers argued.

“Where does this all end?” asked James R. Thompson, a former Illinois governor and a partner at Winston & Strawn LLP who opened the arguments for Philip Morris.

He posed a hypothetical: What would happen if the FTC decided to modify its stance after Philip Morris was forced to pay billions to the plaintiffs?

“Do we then get to file a motion for newly discovered evidence? And do we get to trumpet the latest FTC opinion as that evidence? And do we get our money back?” Thompson asked. “Surely this is not a game of musical chairs depending on who sits in the chairs of the FTC at any given time.”

Lisa S. Blatt, a partner at Washington, D.C.-based Arnold & Porter LLP who also represents Philip Morris, said the FTC’s use of “authorize” amounted to a legal term of art — something that changes with context, like the terms “duty,” “immunity” or “insanity.” Interpretations of those terms don’t amount to hard facts, she said.

Blatt added some context to the strange procedural track the Philip Morris case has followed.

“No court, no court, much less a Supreme Court, has ever, ever overruled itself based on an agency’s amicus brief or statements in the federal register,” she said. “This court should not be the first.”

Neither of Philip Morris’ lawyers were questioned by the justices.

David C. Frederick, a Washington, D.C.-based partner at Kellogg, Huber, Hansen, Todd, Evans & Figel PLLC who represents the plaintiffs, opened his argument by calling Philip Morris’ sale of “light” cigarettes “the most massive fraud in American history.”

Not more than a few minutes in, he was interrupted by Chief Justice Rita B. Garman.

“What authority is there, whether it’s constitutional or statutory or common law, that would allow a lower court to set aside a judgment of a higher court?”

Frederick said the lower court in this case didn’t really set aside or ignore the high court’s original judgment. It had new facts via the plaintiffs’ Section 2-1401 petition for relief that changed the outcome, he said.

“The purpose of 2-1401 by its plain text and legislative purpose is to achieve the right outcome in a case,” Frederick said.

Garman responded immediately.

“Is there anything in 2-1401 that would prevent that petition from being filed in, for example, the Supreme Court?”

Frederick said it was filed in circuit court because “the original jurisdiction for petitions is in the circuit court.”

Justice Anne M. Burke was the only other justice to ask a question.

As he did the last time the case was at the Supreme Court, Justice Robert R. Thomas recused himself. A court spokesman said that was because one of the attorneys for the plaintiffs, Joseph A. Power Jr., represented Thomas in a libel suit roughly a decade ago and because Thomas’ son works for Power’s firm.

But Justice Lloyd A. Karmeier did not. When the court agreed to hear the case a second time, Karmeier filed a 16-page rebuttal to some of the plaintiffs’ lawyers who had called for him to stay out of it.

Karmeier voted with the majority in 2005 to toss the original verdict and did the same with a separate billion-dollar verdict in a case against State Farm Insurance Co.

Lawyers at the plaintiff firms Korein, Tillery LLC; Power, Rogers & Smith and Clifford Law Offices, who were involved in the litigation for the plaintiffs, have long claimed Karmeier knowingly took contributions from groups with ties to Philip Morris before ruling in their favor.

But Karmeier has vigorously denied those claims, writing among other things in his filing that the notion they bankrolled his 2004 high court campaign is “based entirely on conjecture, innuendo and speculation,” and that the firms who represented Philip Morris donated less than 1 percent of the millions he raised that year.

The spat culminated last November when the law firms contributed around $2 million to an effort to unseat Karmeier, using negative TV advertisements that accused him of delivering favorable verdicts for corporations.

But Karmeier narrowly avoided becoming the first Supreme Court judge to go down in a retention election, winning about 60.8 percent of the vote when he needed 60 percent.

On Tuesday, he sat silently through the arguments.