Nick Lutz says the four-page apology note, handwritten on lined white notebook paper, appeared under the windshield wiper of his truck last winter.

It came from an ex-girlfriend whom he had blocked by phone and on social media. She wanted to say she was sorry, and she took some liberties with spelling and grammar in the process.

Lutz, still feeling betrayed by the breakup, saw an opportunity.

Like a teacher grading a paper, he took a bright red pen and savaged it, correcting mistakes and leaving commentary in the voice of a perturbed copy editor. Lutz assigned her a grade, a D-minus and wrote that he would accept “revision for half credit.”

Then he posted a picture of it to Twitter.

“When your ex writes you an apology letter so you grade it to send it back,” Lutz captioned the tweet, which went predictably viral, shared 121,000 times and liked 337,000 times, and spurred a swarm of journalists from across the globe to write about his “savage” words.

That was five months ago.

Now, the University of Central Florida, where Lutz is a rising senior studying sports management, has decided to suspend him over the viral tweet because, the school said, it violated the student code of conduct for being “disruptive” and “harmful.”

Lutz and his attorney, close family friend Jacob Stuart, claim the university’s ruling is unconstitutional and chills student free speech. This week, they appealed in a letter to the UCF Office of Student Conduct that called the decision a “dangerous precedent.”

“I think the damaging thing here is how does UCF decide what’s morally harmful?” Stuart told the Miami Herald. “There was nothing derogatory about it. It was obvious he was making fun of her, but that’s the beauty of the constitution.”

Nick Lutz was suspended from the University of Central Florida five months after sharing his ex-girlfriend's apology letter on social media. (Amber Ferguson/The Washington Post)

Lutz’s punishment includes a suspension from classes for the summer and fall 2017 semesters, probation until he graduates and an assigned mentor, according to the appeal letter. Lutz also must create a presentation on how his “actions in this incident have impacted others” and write a five-page paper on the “impact of this type of behavior in the future,” the letter said.

The university did not immediately respond to a request for comment from The Washington Post, but a UCF spokeswoman told the Miami Herald that the ruling is not yet final.

“It’s important to understand that the process in this case may yet not be complete,” the spokeswoman said.

Lutz and Stuart did not respond to requests for comment late Tuesday night.

Stuart wrote in the appeal that the ex-girlfriend, who felt she was cyberbullied, filed a complaint with the Volusia County Sheriff’s Office, but the case was never prosecuted. She then complained to the university, where she is not a student. Several weeks later, Lutz was called into a meeting with the student conduct and Title IX directors to discuss the tweet.

“Once that hearing was over I knew that they weren’t happy and they were going to do something about it,” Lutz told ABC affiliate WFTV 9 this week.

As most of you know, I graded an apology letter written to me, then proceeded to post it on twitter, where many people…

Posted by Nick Lutz on Monday, July 17, 2017

He received a letter July 6 outlining the sanctions he faced, according to the appeal letter.

Stuart argued in the appeal that Lutz’s tweet was constitutionally protected speech because he did not say anything demeaning, derogatory or threatening. The ex-girlfriend’s first name is visible on the letter, but Lutz never shared her last name, tagged her social media accounts in the tweet or divulged her personal contact information, Stuart wrote.

“The right to enjoy freedom of speech is by no mean absolute,” Stuart said in the appeal. “Yet, there is only specific and extreme situations that this fundamental right is restricted by the government.”

He argued “this type of ‘social media trolling’” by university officials “would lead to thousands of UCF students being suspended, much like Mr. Lutz, due to their comments and posts.”

Stuart also said the university is violating its own Rules of Conduct introduction, which reads:

“The right of all students to seek knowledge, debate ideas, form opinions, and freely express their ideas is fully recognized by the University of Central Florida. The Rules of Conduct apply to student conduct and will not be used to impose discipline for the lawful expression of ideas.”

Posted by Nick Lutz on Thursday, March 23, 2017

In an interview with WFTV 9, Lutz said that the viral tweet was born out of a “joke” conversation with his friends. He sent them a photo of the letter after he discovered it on his truck and one suggested he “grade it” with a red pen.

“My goal was never to expose her,” Lutz said. “It was to show the emphasis on the letter.”

Almost immediately after posting the letter online, he was receiving thousands of social media notifications, text messages, emails and phone calls, Lutz told WFTV 9. Everyone thought the tweet was “hilarious” and “relatable,” Lutz said.

“This is the right thing to do, and I still feel that way, that there’s nothing wrong with what I did,” Lutz told the TV station, explaining that the post symbolized him standing up for himself after what he had previously claimed was a relationship lacking in trust and fidelity.

“I did nothing wrong and I don’t know why [the university is] jumping into my wheelhouse with this because it’s not really much to do with them,” Lutz said.

Though the 21-year-old admitted to feeling “guilty” about the viral tweet in a February interview with the BBC, Lutz told WFTV 9 that he now has no regrets.

“Once it was posted, everyone’s reaction to it I had no control over,” Lutz said, though he never deleted the letter post, which is still easily visible and pinned to the top of his Twitter feed. “It’s portraying me as somebody that I’m not in the end.”

More from Morning Mix:

Muppet creator’s family says fired actor played Kermit as ‘bitter, angry, depressed victim’

Mormon university instructor fired after Facebook post supporting LGBT rights, she says

Cattle-prod wielding rabbi kidnappers fail to convince court they were just practicing their faith

Judge halts sale of Madonna’s love letters and other personal items, which she claims were stolen