In a scary case of political correctness, a projection of a silhouetted figure hanging from a noose — part of Halloween decorations at an NYU Law School costume ball — prompted liberal student groups to pen an angry letter to administrators.

The Fall Ball decor on Oct. 29 showed “triggering, disrespectful, and harmful suicide imagery,” said the law school’s Mental Health Law and Justice Association in an open letter to deans Jason Belk and Trevor Morrison.

“For members of our community who have lost someone to suicide or who have had personal experiences, this topic is not a Halloween gimmick,” it reads.

The projection showed “silhouetted people engaging in what we can only imagine were intended to be ‘spooky’ activities,” according to the letter. “One of the images projected displayed a man dying by suicide.”

The letter demanded an apology “to all members of our community who may have been triggered” by the images.

The offending video was projected onto the windows inside Greenberg Lounge in the law school’s Vanderbilt Hall building during the annual ball, attended by hundreds of students in costume.

A group of law students selected the Halloween theme and the school’s Office of Student Affairs provided decorations.

But one partier described the decorations as “very standard Halloweeny things.”

She was not surprised at the uproar, however.

“NYU tends to be very sensitive to this kind of thing,” she told The Post.

The law school didn’t formally apologize but did issue a conciliatory statement: “We agree that some of the imagery at this year’s Fall Ball was inappropriate, and it won’t be used again,” said NYU Law School spokesman Michael Orey.

Orey said that the dean of students will be meeting with concerned students next week to discuss the matter.