What is the Hart Trophy? The simplest explanation is the...

A Harlem woman took a page out of the script of Oscar-nominated “Three Billboards” — by putting up her own 50-foot highway signs blasting a teacher she accused of raping her two decades earlier.

Kat Sullivan said she was fed up with not being able to bring her rapist to justice under New York state law, so she took out three digital billboards along highways in Albany, Fairfield, Connecticut, and Springfield, Massachusetts.

“I was on a plane and watched ‘Three Billboards’ and got the idea,” Sullivan told The Post on Friday, referring to the drama starring Frances McDormand about a mom who puts up billboards challenging local authorities to solve her daughter’s murder.

Sullivan, now 38, was a student at Emma Willard School — an elite, all-girls private boarding school in Troy, New York — when she says she was blindfolded, ball-gagged and brutally raped in 1998 by history teacher and soccer coach Scott Sargent.

She wound up settling with the school for an undisclosed amount — $14,000 of which she used to pay for messages on three billboards that will run for 28 days.

“He can still teach and coach and he was hired by another school. He got a recommendation,” said Sullivan, a nurse who recently moved to New York City from Florida. “My life was completely ruined.”

Sullivan said Sargent began “grooming” her after he found out her mom was sick with brain cancer and gave her the key to his office so she could call home.

“I thought he was helping. I thought he was being my friend,” she recalled. “He started messaging me on AOL, saying you look really pretty today. It felt nice, the attention. It went from, ‘Hey, I really like you’ to very controlling very quickly, like, ‘Where were you?’”

Years after the attack — which occurred when Sullivan was 18 — she mustered up the courage to come forward, but soon learned the statute of limitations on her case had run out.

In New York state, sex abuse victims have until the age of 23 to press criminal charges or bring a civil action against their alleged abusers.

Sullivan was left with no legal options.

“I would like to see him in a court of law. In New York state, the civil law on this is the same statute of limitations as for a slip-and-fall case,” she said.

“I can’t take him to court, but I can do this,” she added about the billboards.

The billboards are located on I-787 in Albany near Emma Willard, I-95 in Fairfield, where Sargent lived and taught at the Kings School after Emma Willard, and I-90 in Springfield, near where he currently resides.

“My rapist is protected by New York state law. I AM NOT,” one of the billboards reads, with Sullivan’s picture in the center. “NEITHER ARE YOU. NEITHER ARE YOUR CHILDREN.”

One of the billboards urges New York lawmakers to pass the proposed Child Victims Act, which would extend the statute of limitations to age 28 in criminal cases and age 50 in civil cases. The act would also create a one-year “look-back” window to allow victims of any age to bring their abusers to court.

A third billboard features a blank outline of a man with the caption, “The truth will be revealed.”

Sullivan said she’ll publish Sargent’s name and photo on her website, sexualpredatorsouthhadley.com, once the billboards are taken down. He wasn’t identified on the billboards because the company Sullivan used feared a libel suit.

Meanwhile, she welcomes one.

“The ultimate defense for libel is to tell the truth and there has been absolutely none of this embellished,” she said. “I would actually welcome litigation because it would allow me to get discovery and subpoena power.”

Sargent’s abuse was documented in a 127-page report released last April that also revealed Emma Willard students were subjected to decades of sexual abuse by staffers since the 1950s.

Sargent couldn’t be reached for comment.

The Child Victims Act has gotten support from the New York Assembly but has been blocked by the state Senate for years. Now, Democrats are pushing to have the bill included in the budget, which is due April 1.