Irving was long highly regarded for his treasure trove of documents on Hitler and other Nazi officials, he said.
Bartov added that it was important to expose people like Irving, "who has been published by respectable publishers and been cited by scholars like me. But in recent years, he'd become more extreme and associated himself with neo-Nazi circles."
Michael Berenbaum, Distinguished Professor of Holocaust Studies at Clark University in Massachusetts, also said it is important for the court to help set professional standards for historians.
"Instead of going down into the gutter with Irving, we elevated the question into what is the obligation of a historian to interpret evidence and translate material. And Irving was found wanting," said Berenbaum, a former director of research at the U.S. Holocaust Memorial Museum in Washington.
"In a way, Holocaust denial has been defeated over and over and over again," he said.
"A Holocaust museum is built in Washington. Sixty-five million people watch 'Schindler's List.' The German president apologizes to Israel.
"Then what can you say about these guys who say the Holocaust never happened? They're a fringe movement of charlatans."
Daniel Jonah Goldhagen, an associate at the Center for European Studies at Harvard and author of the controversial best-seller "Hitler's Willing Executioners," said that Tuesday's verdict sent a clear message about how to view Holocaust deniers like Irving.
The verdict "should go out as a message" to everyone "that the people who deny the Holocaust are engaging in fraud."
Judge Gray -- the quintessence of British correctness, courtesy and understatement -- did not mince words when he declared Tuesday that Irving was indeed, as Lipstadt had charged, "an active Holocaust denier."
The judge also called Irving "anti-Semitic and racist," saying he has "portrayed Hitler in an unwarrantedly favorable light."
He ruled that Lipstadt had failed to prove some of her claims about Irving, including that he has a self-portrait of Hitler above his desk.
But he added that the unproved charges would not have "any material effect on Irving's reputation."
Pelted with eggs as he entered the court building Tuesday, Irving faces public humiliation and bankruptcy.
After the verdict was announced, Irving said he would not be silenced.
"I will still continue to write what I find to be true history. I can't be intimidated," Irving told Sky television.
Lipstadt said after the verdict was read that although she regrets that Holocaust survivors attending the trial were forced to endure Irving's taunts, "I see this not only as a personal victory but also as a victory for all those who speak out against hate and prejudice."
Jewish groups from all political and religious viewpoints universally praised the ruling.
"Irving tried to manipulate the British legal system in order to put the victims murdered in the gas chambers on trial," the Simon Wiesenthal Center said in a statement. "Instead, the net result is that he will be relegated to the garbage heap of history's haters."
While welcoming the verdict, some observers are sorry that the trial ever took place.
The facts of the Holocaust are the facts," said Sara Bloomfield, director of the U.S. Holocaust Memorial Museum. "We didn't need a trial to prove that the Holocaust happened."
She described Irving as a "pretty frivolous and mean-spirited individual seeking a lot of public attention" and bemoaned the fact that Lipstadt "had to take months out of her life and her scholarly work" to deal with Irving's lawsuit.
For his part, Bartov of Rutgers University admitted that he hadn't closely followed the Irving trial.
"Personally, I'm rather ambivalent about the whole public debate about Holocaust denial," he said. "It's a rather marginal phenomenon, and most of the people who use this rhetoric are marginal people.
"Arguments that there were no gas chambers at Auschwitz are for cranks. It's as if someone said, 'I am Napoleon.' It's somewhat bizarre to have to debate it. It places cranks in the center of a public debate, rather than where they belong, which is at the margins."
Even with the verdict against Irving, the assault on historical truth is far from over.
A greater threat than Holocaust deniers are mainstream, nationalist leaders in Europe, said Randolph Braham, director of the Rosenthal Institute for Holocaust Studies at the City University of New York.
"They are respectable, believable leaders who don't deny the Holocaust but distort it or denigrate it to cleanse a particular history," said Braham, an expert on Hungarian and Romanian Jewry.
The threat from such leaders should not be underestimated, he added.
"As George Orwell said, 'Those who control the present control the past; those who control the past control the future.' ''
JTA staff writers Peter Ephross and Michael J. Jordan in New York also contributed to this report.