An Israeli legal group sent more than 100 US college and university presidents a letter this month, warning them to crack down on anti-Semitism and terrorist activities.

Seems reasonable enough. But the letter, drafted by the Israel Law Center, contains suggestions that come perilously close to stunting First Amendment protections for unpopular speech.

“[A]lthough academic and political freedom in the United States is a cherished right, there are limits to these rights that students and campus officials must be made aware, especially with regard to anti-Israel activities,” the letter from the Israel-based legal group said. “[A] Jewish student should feel safe enough to publicly wear his yarmulke across campus and not fear verbal or physical anti-Israel abuse.”

Threats of physical violence are not to be tolerated, and against these wrongs US courts stand unequivocally.

But let this also be clear: Anti-Israel speech is protected by the full force of the First Amendment. Vehemently. And such speech is permissible on American college and university campuses.

US law has long defended Americans’ right to criticize governments, and even to spread seditious libel, that is, defamatory speech about governments.

Anti-government speech cannot be conveniently labeled “harassment” or “abuse” whenever detractors would like it to stop. Anarchists may hold an anti-US government demonstration on, say, the University of Virginia campus and, perhaps with the appropriate permit, burn American flags. Such a protest cannot, however, be branded harassment by the Daughters of the American Revolution for the purposes of abridging any offensive speech.

The US Supreme Court decided in March in Snyder v. Phelps that members of the Westboro Baptist Church, who protest near funerals of US soldiers and shout the vilest slurs, could not be sued for intentional infliction of emotional distress, despite the foulness of their campaign. The Supreme Court ruling was not close; justices voted 8-1 in favor of the Westboro rabble-rousers.

If the First Amendment protects such hateful speech, it very obviously protects acerbic speech about Israel, and even about Jews or other minority groups. British fashionisto John Galliano was convicted in a French court this month and fined over $8,000 for anti-Semitic slurs he mumbled while swaying atop a Parisian bar stool, but such punishment of speech in the US is unthinkable.

In 2005, The Daily Tar Heel, the campus newspaper of The University of North Carolina, published a racist opinion column by student Jillian Bandes, who said she wanted “all Arabs to be stripped naked and cavity-searched if they get within 100 yards of an airport.” The university did not, indeed could not, take action against Ms. Bandes. She was subsequently fired for the column by the student editor, but only because she deliberately strung together quotes from an Arabic professor and student to affect their meaning.

American universities have high thresholds for the tolerance of nasty speech, as they should. One of the grandest functions of college and university presidents in the United States is not to curb unpopular speech, but rather to protect it.

At the University of Maine where I teach, campus preachers may (and do) shout bigoted remarks about homosexuals and where they’ll go in the afterlife. Those slurs and other vile speech about minority groups are protected on the campus of a public university.

The United States and Israel share a number of similar legal traditions, including the existence of powerful supreme courts that often rule against the wishes of legislators and even public opinion. But many of Israel’s and other nations’ limits to speech violate very basic understandings of liberty and dissent in the US.

Lee Bollinger, president of Columbia University and a First Amendment scholar, wrote disapprovingly in 2010 that, “even those that are nearest to the United States in their commitment to a democratic form of government (such as Great Britain, Germany, and France) have sometimes arrived at a different balance when it comes to the press and other societal interests.”

Anti-Semitic speech is not protected in the US in some limited instances, such as when it involves slurs directed at a specific individual, which may amount to harassment. Anti-Israel speech, though, is anger directed at an institution – a government. The laws of the United States are abundantly clear that such expression is protected to the full.