Now the backlash to pro-Palestinian activism is building. On Tuesday, Penn’s president, along with the presidents of Harvard and M.I.T., is scheduled to appear before Congress for a hearing titled, “Holding Campus Leaders Accountable and Confronting Antisemitism.” Both New York University and Berkeley are being sued by people who claim that they’ve allowed antisemitism to flourish. Big donors at several schools are yanking funding. Chris Rufo, the right-wing activist who whipped up nationwide campaigns against critical race theory and diversity, equity and inclusion initiatives, told me he’s part of a group at the conservative Manhattan Institute workshopping new policy proposals targeting what it sees as campus antisemitism.

But there’s a fierce political debate about what antisemitism is. Supporters of Israel often promote a definition of antisemitism put out by the International Holocaust Remembrance Alliance in 2016 that defines rejection or demonization of the Jewish state as a form of anti-Jewish bigotry. According to the alliance’s definition, one example of contemporary antisemitism is “claiming that the existence of a state of Israel is a racist endeavor.” Another is applying double standards to Israel by “requiring of it a behavior not expected or demanded of any other democratic nation.” The question of what constitutes double standards is not one that can be easily codified, and one of the experts who helped draft the alliance’s definition argues against its use to circumscribe campus speech.

Nevertheless, that definition keeps gaining legal traction. The Trump administration issued an executive order adopting it for the purposes of enforcing federal civil rights law. Last month the House passed an amendment to an appropriations bill that would deny federal funds to any college or university that “authorizes, facilitates, provides funding for, or otherwise supports any event promoting antisemitism” under the definition. This week, the House will vote on a resolution embracing the definition and proclaiming that “anti-Zionism is antisemitism.” Some schools, including Harvard, are facing alumni pressure to adopt the alliance’s definition on their own, and the definition is key to the lawsuit against Berkeley.

I asked Chemerinsky, a leading scholar of free expression, what it would mean for schools to enforce a ban on antisemitism as defined by the alliance. “I don’t know how it could possibly be at a public university without violating the First Amendment,” he said.

When it comes to free speech, “Israelism” should be an easy case. Others are trickier. As I write this, the internet is ablaze with outrage over a teach-in planned for this week by Columbia Social Workers 4 Palestine about the “counteroffensive on Oct. 7 and the centrality of revolutionary violence to anti-imperialism.” This rhetoric, with its grotesque mixture of euphemism and dogma, was disgusting, but it was still a mistake for the school to cancel the event on Monday; better allow the organizers to disgrace themselves in public than pose as silenced heroes. Given the growing pressure on school leaders from Israel’s partisans, administrators are going to feel a growing temptation to err on the side of censorship. If we don’t want escalating bigotry to enable escalating repression, we need to err on the side of speech.