Until a few minutes ago (at least in my browser), a Washington Free Beacon article stated,

Police in Garwood, New Jersey, ordered that a militant flag associated with the Islamic State of Iraq and the Levant (ISIL or ISIS) be removed from the front of a local home after hundreds of online activists expressed fear and revulsion….
“Thank you for your concern regarding this important matter,” Underhill wrote the Free Beacon in an email Wednesday afternoon. “Only with the public’s continued cooperation can we keep our communities safe.”
“Please be assured that the Garwood Police are aware of the situation and have taken the appropriate steps,” Underhill wrote. “At this time, the flag in question has been voluntarily taken down. No further comments.”

If this were so, it would violate the First Amendment. Just as the First Amendment protects the right to display Nazi flags or Communist flags, or to burn American flags, so it protects the right to display the Islamic State’s flag, repulsive as the organization it represents is. (I’m assuming for purposes of the post that the flag was indeed a flag of the Islamic State of the Iraq and the Levant.) Nor can the flag be dismissed as “fighting words,” just as the burning of the American flag can’t be suppressed on such grounds. As the Court held in the flagburning case (and other cases before it), fighting words are limited to “a direct personal insult or an invitation to exchange fisticuffs”; flag displays are not sufficiently “personal,” unless there are some highly unusual facts present.

Since then, the story has been updated to say that, “[f]ollowing publication of the story, Garwood Police Chief Bruce D. Underhill denied that the police ‘ordered’ the flag to be removed,” and it’s hard for me to opine on the actions of the police without knowing more about what those actions were. If the police came to the house and warned the owners of the hostility that their flag is engendering, that would likely be constitutional. If they demanded that the flag be taken down, or threatened the owners with retaliation or deliberate denial of police protection, that would be unconstitutional. But I did want to stress that such flag display is fully constitutionally protected.

Thanks to Louis Offen for the pointer.