By Terry Baynes

NEW YORK (Reuters) - U.S. Supreme Court Justice Antonin Scalia on Monday escalated a war of words with a prominent appeals court judge, saying the judge lied in a recent criticism of Scalia's judicial philosophy.

Scalia, 76, the longest-serving justice and a leading conservative on the court, said Judge Richard Posner, of the 7th U.S. Circuit Court of Appeals, lied in a review in August of a book co-authored by Scalia.

In the review, Posner accused Scalia of deviating from his own strict, text-based approach to interpreting law when he struck down a District of Columbia handgun ban in 2008 by considering the legislative history behind the law.

"To say that I used legislative history is simply, to put it bluntly, a lie," Scalia said in an interview with Reuters Editor-in-Chief Stephen Adler.

Scalia and legal scholar Bryan Garner were discussing their new book, "Reading Law: The Interpretation of Legal Texts," published by West, a unit of Thomson Reuters.

The 567-page book sets out the legal philosophy, called "textual originalism," which says judges should adhere strictly to the text of laws and give them the meaning understood by the people who adopted them. Laws do not change in meaning over time, they contend.

The book has sparked a heated debate in legal circles after Posner accused the authors of making flawed arguments based on sloppy research. Posner said numerous cases that the authors held up as models of text-based decisions were influenced by other factors, including judges' personal views.

Scalia fanned that debate on Monday, saying Posner was only able to make such an assertion because he was writing in a non-legal publication, The New Republic. "You can get away with it in The New Republic, I suppose, but not to a legal audience."

Posner declined to comment on Monday night.

As an example of originalism, Scalia said the death penalty was not covered by the U.S. Constitution's prohibition against cruel and unusual punishment. At the time that clause was adopted, he said, the death penalty was a standard punishment for a felony. If people want to ban it, they must amend the Constitution or vote to abolish it at the state level, he said.

When asked what happens when linguistic analysis of a law conflicts with existing court decisions, Scalia said that judges cannot reinvent the wheel, particularly if precedent has been in place for a long time.

"We are textualists. We are originalists. We are not nuts," he said.

One prominent exception to that is Roe v. Wade, the Supreme Court's 1973 ruling that legalized abortion. He does not consider that binding precedent, he said, because it was wrong, remains controversial and is an issue better left to legislators than judges.

What's more, the court's subsequent decisions on abortion are based on the judge-made theory of "substantive due process," which guarantees certain fundamental rights like privacy. It's "utterly idiotic," Scalia said.

Scalia said he accepts being frequently on the losing side of Supreme Court decisions, because that's what it takes to follow his philosophy of sticking to the letter of the law.

And he said he was happy to be out of the running for the role of chief justice, with its pressures of having to build a consensus among the nine justices. Former Chief Justice William Rehnquist had to temper his approach after being promoted to chief, he said.

"He was a shin kicker. He was very, very opinionated," Scalia said. "He changed when he became chief. I didn't have to worry about that."

Scalia emphasized that taking a principled approach, rooted in the original meaning of the text of laws, does not necessarily lead to socially and politically conservative results, as some have argued.

"I should be the pinup of the criminal defense bar," Scalia said, pointing out originalist opinions have strengthened defendants' right to a trial by jury and to confront opposing witnesses.

Scalia acknowledged that today's court can be divided more easily along political lines than in the past. But he bristled at hearing the court described as political.

"It really enrages me to hear people refer to it as a politicized court," he said. His colleagues were appointed because of who they are, and that informs how they vote, he said.

In its biggest decision of the past term, the Supreme Court on June 28 ruled to uphold President Barack Obama's healthcare law, handing the president and fellow Democrats an election-year victory.

In that decision, Chief Justice John Roberts surprisingly joined the court's four liberal members to uphold the law's key provision, which requires that most Americans buy health insurance or pay a tax. Scalia joined in a sharply worded dissent. Subsequent media reports suggested that tempers had flared between Scalia and Roberts, reports that Scalia has rejected.

On Monday, Scalia largely steered clear of discussing the healthcare deliberations and ruling. He did, however, respond to an audience member who asked about a 1798 law requiring merchant seamen to obtain health insurance. The federal government has powers over admiralty and shipping that it does not have over the average citizen, Scalia responded.

When asked about whether television cameras should be allowed in the courtroom during oral arguments, Scalia said his views on the subject had evolved. When he first went onto the bench, he thought televising courtroom proceedings would help educate the American public. Now, he thinks the opposite.

The vast majority of the court's time is spent grappling with the intricacies of laws like the Internal Revenue Code and the Employee Retirement Income Security Act, not "contemplating our navel" about the right to abortion, he said. But people will see a 30-second clip on the nightly news that will give them a misimpression of the court.

(Reporting by Terry Baynes; Editing by Eddie Evans and Lisa Shumaker)