Liberals have been busy lately lecturing about right-wing threats to Israeli democracy. What happens when some liberals stumble, forgetting that liberty must be preserved for all, even if the “wrong” people exercise power or publish newspapers? I offer today an Et tu Brute, echoing Julius Caesar’s legendary protest against betrayal, written in sorrow, to some of my intellectual heroes for violating their own core ideals.“Scholars for Israel and Palestine” (SIP) wants “the United States and the European Union to impose personal sanctions on a cluster of Israeli political leaders and public figures who lead efforts to insure permanent Israeli occupation of the West Bank.” Their petition targets Naftali Bennett, Uri Ariel, Moshe Feiglin, and Zeev Hever as “four powerful Israeli … public figures who promote these unjust, unlawful, and destructive policies in their most extreme and dangerous form,” making them “legitimate targets” for attacks by foreign governments on their freedoms, including “visa restrictions and foreign asset freezes.” Shockingly, among the twenty academics who signed were luminaries of the thoughtful, Zionist Left whom I revere such as Michael Walzer and Todd Gitlin. That they propose fighting citizens whose ideas they hate with state power rather than intellectual firepower – even if another state’s power -- betrays the example each has set in lifetimes committed to peaceful, substantive, iconoclastic dissent. Their computers should have had a civil libertarian autocorrect to save them from such lapses.What happened to Thomas Jefferson’s First Inaugural teaching that foolish ideas can be left to “stand undisturbed as monuments of the safety with which error of opinion may be tolerated where reason is left free to combat it?” What happened to faith in John Stuart Mill’s free marketplace of ideas? These teachings about the value of sustained debate are particularly relevant because the SIP petition rests on assumptions about international law, the 1967 territories’ status, and the organic nature of those territories, that many good, smart, sincere people have been debating for decades now – without having their assets threatened or freedom of movement menaced. The petition says “UN Security Council Resolutions 242 and 338 allowed for a temporary Israeli occupation in the territories captured in the 1967 war, while calling for a negotiated peace settlement that would include Israeli withdrawal from occupied territories…”; the missing “the” before the second mention of “occupied territories” reflects the longstanding debate. After 1967, Israel accepted the principle of withdrawing from some territories but not all the territories because the West Bank’s status was legally murky and Israel has valid counter-claims, especially to Jerusalem’s Old City and Gush Etzion. Overriding – or criminalizing – debate about that is criminal.Similarly, SIP’s dismissal of Naftali Bennett’s New York Times op-ed of November 5, 2014 with one throwaway line is misleading. The SIP attack treats all four settlement hawks as expansionist ideologues. Bennett’s op-ed cleverly, effectively, focused on Israel’s legitimate security concerns and Palestinians’ ongoing war against Israel. Refute him, don’t muzzle him.Although the petition distanced itself from calls to boycott Israel, undemocratically demonizing Israeli politicians takes unhealthy steps in that direction. It smells of panic on the pro-Israel Left, desperate to remain popular as even many mainstream liberals lose patience. It reflects an unhealthy obsession and oversimplification regarding Israel’s complex, fragile position in the territories, following the post-Oslo terrorism epidemic. It plays into campus presumptions treating Israel’s occupation as the great crime of the century, meriting such extraordinary countermeasures – countermeasures that have not been proposed for the Chinese despoilers of Tibet or Palestinian Authority kleptocrats who exploit their own people, to name just two far more legitimate targets. Criminalizing the debate reflects a disturbing hardening of positions within the Zionist Left that overlooks the moral, political, historical, and security ambiguities that make this conflict so intractable. SIP’s framing and strategy blindly endorses the Palestinian conceit treating the West Bank as some kind of organic, authentic, untouchable, undisputed geopolitical entity with clear rather than improvised and malleable borders.I understand the frustration and the fear. But just as it was despicable for Knesset “liberals” to support the anti-Israel Hayom law trying to ban free newspapers, it is reprehensible for civil libertarians to try squelching this important debate with state bullying. The anti-democratic forces in Israel today don’t need the kind of modeling and encouragement SIP perversely provided. When leaders from the Left who purport to support democracy nevertheless outlaw free newspapers or punish free thought, they share same contempt for democracy right-wing hooligans show. Can you imagine the outrage if the Knesset tried shutting down Ha’aretz rather than a newspaper Sheldon Adelson supports? Can you imagine the fury if American academics asked their government to “sanction” Arab Knesset members for encouraging terrorism or Israeli peaceniks because withdrawal from territories has resulted in lethal rocketing and terrorism? Aren’t mutuality, consistency, and integrity foundational democratic values, Left and Right?Justice Oliver Wendell Holmes, Jr., said it best: “Persecution for the expression of opinions seems to me perfectly logical. If you have no doubt of your premises or your power, and want a certain result with all your heart, you naturally express your wishes in law, and sweep away all opposition.” That, to my surprise and disgust, is what these petitioners proposed. I am still old-fashioned enough to believe in the power of debate. I am desperate for heroes from the Left and the Right to model this kind of behavior civilly, substantively, productively and consistently, as Walzer and Gitlin have done for decades. I will fight these totalitarian tendencies from the Left to close newspapers they hate or harass politicians they abhor as ardently as I fight parallel barbarities from the Right. Democracy requires that kind of faith in its processes, even when we abhor some outcomes. Gil Troy is a Professor of History at McGill University and a Visiting Professor at the Interdisciplinary Center in Herzliya. His latest book, Moynihan's Moment: America's Fight Against Zionism as Racism, just received the 2014 J.I. Segal Non-fiction Award on a Jewish Theme. Watch the new Moynihan's Moment video!