Kudos to American television comedian David Letterman! On June 5, 2011, Letterman smiled and drew his finger across his own throat on his CBS program “Late Show with David Letterman” to celebrate the U.S. military’s reported killing of Ilyas Kashmiri, an Islamist terrorist who apparently was the head of Harkat-ul-Jihad al-Islami and a senior al-Qaeda leader. Kashmiri reportedly was one of the leading organizers of the deadly November 2008 Mumbai attacks in India, which killed 164 innocent people and wounded at least 308. He was also recently indicted in U.S. federal court for conspiring with other terrorists to plan a Mumbai-style attack in Denmark, directed at the newspaper Jyllands-Posten, the newspaper that had published the infamous Mohammed cartoons. For good measure, Letterman also insulted Osama bin Laden during the same broadcast.

Letterman’s understandable sentiment provoked a serious reaction from a group of radical Islamists. These Islamists — who themselves frequently express their joy at the murder of Americans — took offense at Letterman celebrating the killings of two mass murderers. In a posting on the Islamist web forum Shumukh al-Islam, they called for Letterman’s murder, and encouraged the killer to cut off Letterman’s offending tongue. The posting also mistakenly labeled Letterman a “Jew,” which to millions of Islamists is the ultimate insult.

To his immense credit, David Letterman did not back down. He and CBS tightened security at the Manhattan theater where they tape the “Late Show,” and Letterman increased his own security. Then, rather than buckle under, he made light of the threat in a subsequent appearance on his show. Among other things, he thanked his audience, saying: “You people are more than an audience tonight. You’re more like a human shield.” He even drew up one of his famous “Top Ten” Lists for the occasion.

David Letterman should be saluted for his courage. He did everything exactly right. Even while taking prudent protective precautions, he refused to apologize for his free speech, or to censor himself. He even went a step further, by returning to the sensitive topic and actually making fun of those who would harm him. Considering how comically challenged Islamists can be, and how bloodthirsty, this took extraordinary courage.

Hopefully, this is the start of a new trend. The past is littered with examples of Westerners — including other comedians — who shied away from expressing their opinions, or apologized in the aftermath, out of fear of Islamist threats. Some of the most prominent examples are:

• The Danish Mohammed cartoons — While Jyllands-Posten had the gumption to post the 12 cartoons of Mohammed in 2005, most other Western newspapers refused to follow the Danish newspaper’s lead. They feared that publishing these cartoons would lead to protests and violence across the Muslim world — and in their own offices. Indeed, violent mobs did wreak havoc after the cartoons were published — at least in part at the instigation of one or more Arab governments — resulting in a total of more than 200 deaths throughout the world. Only a handful of American news outlets had the courage to print the cartoons.

• Yale University — In August of 2009, Yale University Press published a scholarly book on the Danish cartoon controversy — “The Cartoons that Shook the World,” by Brandeis University professor Jytte Klausen. But after consulting more than two-dozen experts on Islam, terrorism and diplomacy, Yale ordered the offending cartoons excised from the book, for fear they would incite further violence from Muslim extremists. In other words, in an act of cowardly censorship, Yale published a book on the carton controversy but omitted the cartoons themselves.

• South Park — In 2006 and then again in 2010, the satiric television cartoon South Park, drawn by Trey Parker and Matt Stone, aired four episodes that simply depicted Mohammed. Both times, Islamists threatened the artists and Comedy Central personnel with death for “insulting” the religious leader. In response, Comedy Central censored the four “offending” episodes, first just by blocking out the Mohammed depiction, but later also by muting much of the speech. Ironically, the censored matter included criticism of censorship and a speech against intimidation, in addition to every use of the name “Mohammed.” In 2011, Comedy Central also edited Mohammed out of the DVDs of South Park seasons, including a 2001 depiction that had never before drawn any controversy. To their credit, Parker and Stone opposed Comedy Central’s self-censorship.

• Molly Norris — In 2010, in response to Comedy Central’s self-censorship of South Park, Molly Norris, a cartoonist for the Seattle Weekly, came up with an idea: “Everybody Draw Mohammed Day.” The point she wanted to make was that freedom implies the right to criticize and caricature, and that this freedom was now in jeopardy. Soon threatened with death by an al-Qaeda imam, Norris quickly retracted her proposal — but it was too late. On September 15, 2010, the Seattle Weekly informed its readers: “You may have noticed that Molly Norris’ comic is not in the paper this week. That’s because there is no more Molly. The gifted artist is alive and well, thankfully. But on the insistence of top security specialists at the FBI, she is, as they put it, “going ghost”: moving, changing her name, and essentially wiping away her identity. She will no longer be publishing cartoons in our paper or in City Arts magazine, where she has been a regular contributor. She is, in effect, being put into a witness-protection program — except, as she notes, without the government picking up the tab …”

• Penn & Teller — Even the irreverent comedy team of “Penn & Teller” has deliberately decided not to subject Islam to the same ridicule they heap on other religions, especially Christianity, because they’re afraid of being attacked. Penn Jillette openly admitted as much in an interview — when he also said that Islam is immune from their jokes because “we have families.”

This is not how free speech is supposed to work in a democratic society. No other religion is protected from being challenged, or even from being verbally attacked.

David Letterman, who also has a family, stood up to Islamists threatening to kill him for his speech. We at the Legal Project recognize that Letterman has far more resources than most to try to protect himself and his family. But even their wealth can’t fully protect them from terrorist reprisal. Yet Letterman did not allow fear to silence him. His example is important, not least because Letterman is so prominent, and this incident is so public. Let’s hope he spurs others to follow in his footsteps, so that threats and intimidation do not silence free expression in this country on any topic.

Adam Turner serves as staff counsel to the Middle East Forum’s Legal Project. He is a former counsel to the Senate Judiciary Committee where he focused on national security law.