In its recently filed lawsuit, the Islamic Society of Boston claimed that one of the defendants, terrorism expert and award-winning investigative journalist Steven Emerson, is "widely regarded as a discredited, biased, self-proclaimed 'expert' on radical Islam ... with a known agenda against Muslims."

Looking at the two decades during which Mr. Emerson has been busy exposing Islamists and the security threats they pose, however, it is difficult to determine how ISB can claim that he is "discredited."

Mr. Emerson can be overly aggressive or too hard-charging for some people's tastes (having worked with him on a limited basis in the past, I should know), but there is no denying that he has been right again and again - and each time long before almost anyone else. When no one was listening to him in the early 1990s, he used hidden cameras for his award-winning 1994 PBS documentary "Jihad in America" to capture supposed moderates spewing venom and vitriol behind closed doors.

ISB's suit is the latest in a string of legal actions brought by Islamist organizations nationwide in a transparent attempt to stifle even legitimate criticism. Even in that context, the Boston mosque has been particularly active. Mr. Emerson is only one victim of ISB's campaign of intimidation-by-lawsuit.

Despite having little chance of winning, ISB's suit could nonetheless cause Mr. Emerson and the other 15 defendants a serious headache - and cost each of them a mint in the process. ISB is simply attempting to do what so many other Muslim groups have done across the country: make others think twice before criticizing.

Here's the background. In 2002, ISB cut a sweetheart deal with the city of Boston, buying nearly 2 acres of prime real estate at the fire-sale price of $175,000, less than half of the $400,000 at which the relevant city agency had it appraised. But according to the Boston Herald, "The Islamic Society of Boston's own newsletter said the land is worth $2 million."

Various local media outlets began looking into ISB once the deal was announced, and what they found was shocking - especially since ISB, like so many others, had positioned itself as decidedly moderate.

Among the most damning evidence to emerge were the ISB's connections to two high-profile radical Muslims, and the fact that the mosque's longtime leader was a co-founder and former vice president of a virulently anti-American and anti-Semitic organization that apparently raised truckloads of cash to support Islamic terrorism.

The Boston mosque was co-founded by, among others, Abdurrahman Alamoudi, who was sentenced to 23 years in 2004 after he pleaded guilty to assisting in a plot to assassinate the leader of Saudi Arabia. But even if ISB can be taken at face value that Alamoudi had no involvement for the past "15 or 20 years," it seems clear that a radical cleric from Qatar, Sheik Yusuf al-Qaradawi, did. Famous because of his fiery fatwas, the sheik hardly represents the moderate brand of Islam to which ISB supposedly adheres.

The sheik, whose Al Jazeera television show has become a phenomenon in the Muslim world, is an active cheerleader for Palestinian suicide bombers, has issued religious edicts encouraging the mass murder of Americans in Iraq, and has called for the murder of all apostates (those who convert away from Islam) and homosexuals.

ISB understandably tried to distance itself from the sheik once his radicalism became known, telling the Herald that the cleric "never played any role in the ISB." The mosque chalked up the appearance of the sheik's name on its tax filings from 1998-2000 as a member of the board of directors as "an administrative oversight." Yet the sheik wasn't just listed as a board member on tax forms; he was also listed as such on ISB's Web site through at least March 2001.

Far more troubling, though, is that ISB's leader for more than a decade was earlier deeply involved in Muslim Arab Youth Association. Osama Kandil was one of nine co-founders of MAYA - along with Osama bin Laden's nephew, Abdullah - and then served as its vice president for several years.

At a mid-1990s MAYA conference, the keynote speaker, the head of "the Hamas military wing," told the crowd: "Finish off the Israelis. Kill them all! Exterminate them!" according to an FBI memo written shortly after September 11. The crowd responded enthusiastically, as more than $200,000 was raised at the event for the terrorist organization, according to the memo.

When asked by the Herald about MAYA, Mr. Kandil defended it as moderate.

With so much incontrovertible evidence demonstrating that ISB is anything but moderate, its lawsuit seems like a surefire loser-but only in the sense of winning a final verdict. Litigation is costly, even defending against a case as flimsy as ISB's.

Last month, Mr. Emerson and his Investigative Project on Terrorism filed a lengthy brief urging the court to dismiss ISB's nuisance suit. Unfortunately for Mr. Emerson and the other defendants, the process could drag on for many more months - or longer.

But if the judge allows the ISB to secure victory by running up the legal tabs of the defendants - thus potentially silencing other would-be critics - the real fear for all of us must be: How many other radicals will learn the lesson and head to court?