â€œIn any war between the civilized man and the savage,â€ says the ad, â€œsupport the civilized man. Support Israel. Defeat jihad.â€

On September 6, the American Freedom Defense Initiative (AFDI) signed a contract to buy space for this message from the Washington Metropolitan Area Transit Authority (WMATA), which had concluded that the First Amendment required it to accept the controversial ad. Less than two weeks later, WMATA declared that AFDIâ€™s advocacy was not constitutionally protected after all, pointing to violent Middle Eastern protests blamed on Innocence of Muslims, an online video mocking the prophet Muhammad.

The idea that riots in other countries justify censorship in the U.S. represents a new form of hecklerâ€™s veto, making freedom of speech contingent on the predicted responses of the touchiest listeners anywhere in the world. Such a policy is dangerous to freedom of expression, providing a license to suppress speech deemed provocative, and to public safety, encouraging violence aimed at eliminating offensive messages.

WMATA said it was indefinitely postponing placement of the AFDI ad because of concerns about â€œsecurity and safety.â€ Specifically, as U.S. District Judge Rosemary Collyer noted in an October 12 opinion explaining why she had overturned the transit authorityâ€™s decision, â€œWMATA cited two ways in which the ad could threaten public safety: (1) inter-passenger disputes on subway platforms that could result in passengers falling into the tracks or (2) a terrorist attack.â€

Collyer mentioned no evidence supporting the first fear, which gives new meaning to the phrase â€œthird rail of American politics.â€ And the only evidence of a terrorist threat was a general warning from the Department of Homeland Security and the Transportation Security Administrationâ€™s opinion that â€œWMATAâ€™s Metrorail system is a unique target because of its close association with the federal government.â€

Meanwhile, the same AFDI ad had appeared in the San Francisco and New York transit systems without prompting terrorism or platform fights in dangerous proximity to electrified tracks. The closest thing to violence was a spray-paint assault on a subway ad in New York by the Egyptian-American journalist Mona Eltahawy.

Collyer nevertheless deemed WMATAâ€™s concerns â€œcompelling,â€ part of the â€œstrict scrutinyâ€ test for content-based restrictions on speech in a â€œdesignated public forumâ€ such as a transit systemâ€™s advertising space. But was banning the AFDI ad â€œnarrowly tailoredâ€ to protect passenger safety?

Not so much, Collyer ruled. She said WMATA instead could have moved the ads away from those dangerous subway platforms, or it could have displayed them with disclaimers expressing its â€œdisagreement.â€

Collyer also rejected WMATAâ€™s argument that calling Israelâ€™s enemies â€œsavagesâ€ amounted to â€œfighting words,â€ which according to a 70-year-old Supreme Court decision can be punished because they â€œtend to incite an immediate breach of the peace.â€ The â€œfighting wordsâ€ doctrine, which the Court never again used to uphold a conviction, applies only to insults spoken to someone in person.

Although Collyer reached the right result, her openness to the argument that speech can be restricted based on the anticipated violence of people it offends was troubling. So was her description of the AFDI ad as â€œhate speech,â€ a constitutionally irrelevant category.

The hecklerâ€™s veto also remains a threat in New York, where the Metropolitan Transportation Authority (MTA) initially turned down the AFDI ad on the grounds that it â€œdemeanedâ€ Muslims. U.S. District Judge Paul Engelmayer rejected that rationale in a July 20 ruling.

On September 27, three days after the AFDI ad began appearing in subway stations, the MTA adopted a new policy barring any message it â€œreasonably foresees would imminently incite or provoke violence or other immediate breach of the peace.â€ For defenders of free speech, those are fighting words.