By Terry Baynes

Sept 20 (Reuters) - A prominent appeals court judge fired a new salvo on Thursday in an unusual public spat with a U.S. Supreme Court justice.

The dispute is between Judge Richard Posner, a prolific jurist who sits on the 7th U.S. Circuit Court of Appeals in Chicago, and Justice Antonin Scalia, a leading conservative on the Supreme Court.

In August, Posner wrote a review of a book co-authored by Scalia. The review said that Scalia's judicial opinions deviated from the strict, text-based approach to interpreting law espoused in his book.

The review pointed to a 2008 decision authored by Scalia in which the Supreme Court struck down a handgun ban in the District of Columbia. That decision was based not just on the text of the law but also on the legislative events leading to its passage, Posner said in the review.

On Monday, in an interview with Reuters Editor-in-Chief Stephen Adler, Scalia said that was not true. "To say that I use legislative history is simply, to put it bluntly, a lie," Scalia said.

Scalia also said Posner had misused the term "legislative history."

Now Posner has fired back in a two-page response that he provided to Reuters. "Responding to a Supreme Court Justice who calls one a liar requires special care in expression," Posner said in an accompanying email.

In the response, Posner said he was neither lying nor mistaken in his critique.

"Even if I accepted Scalia's narrow definition of 'legislative history' and applied it to his opinion in Heller, I would not be telling a 'lie,'" Posner wrote in his response. District of Columbia v. Heller is the Supreme Court decision striking down the Washington handgun ban.

In the interview with Reuters on Monday, Scalia said "legislative history" refers to history of the enactment of a bill in the legislature and covers floor speeches and prior committee drafts, not "the history of the times."

Scalia also called legislative history "garbage" and "the last remaining fiction of the common law," noting that lobbyists can get such history inserted into the legislative record to change the meaning of the text that is adopted.

In his response on Thursday, Posner defended his use of the term, writing that Scalia was using legislative history in the gun rights case when he turned to a "variety of English and American sources from which he distilled the existence of a common law right of armed self-defense that he argued had been codified in the Second Amendment."

Scalia may define "legislative history" narrowly, Posner wrote, but his co-author, Bryan Garner, does not. Posner quoted a definition from Black's Law Dictionary, of which Garner is the editor, that describes "legislative history" as: "The background and events leading to the enactment of a statute, including hearings, committee reports, and floor debates."

"Background and events leading to the enactment" of the Second Amendment are the focus of Scalia's opinion in the gun rights case, Posner argued.

He also cited pages from the opinion that discuss the Second Amendment's drafting history, which he called "legislative history in its narrowest sense."

Scalia, 76, is the longest-serving justice on the Supreme Court. Neither he nor his co-author, legal scholar Bryan Garner, responded to requests for comment on Thursday.

In their book, "Reading Law: The Interpretation of Legal Texts," Scalia and Garner say judges should rely on the text of a law as understood by the people who passed it, not its legislative history, to determine its meaning.

The book is published by West, a unit of Thomson Reuters , which also owns Reuters.

Posner, 73, was appointed as a federal appeals court judge by President Ronald Reagan in 1981 and has written dozens of books, including one about economics and intellectual property law. He also is a founding author of the Becker-Posner blog on law and economics.

In June, he tossed out one of the biggest court cases in Apple Inc's smartphone patent b attle, ruling that the iPhone maker could not pursue an injunction against Google Inc's Motorola Mobility unit over smartphone technology.

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