The University of Alabama's decision to expel Harley Barber over racist videos she posted on social media was unconstitutional and should be rescinded, three prominent civil rights activists urged in an open letter to the college's president.

While the former American Civil Liberties Union officials said they were "dismayed and disgusted" by Barber's videos, her expulsion was "unconstitutional, un-strategic and likely to be ineffective," they wrote.

Barber, a 19-year-old from Marlton, has since returned to New Jersey and apologized.

"The University of Alabama is an educational institution, and this was a teachable moment that you should not squander," the three civil rights activists wrote, asking University of Alabama President Stuart R. Bell to allow Barber to return.

Harley Barber was expelled from the University of Alabama earlier this week after posting videos in which she used racial slurs.

The teen made national headlines this week after posting videos in which she repeatedly said the n-word and made disparaging comments about black people. In two videos posted to her "finsta" or "fake" Instagram on Martin Luther King Jr. Day, Barber says "I (expletive) hate (n-word,)" and claims that she can save the n-word as much as she pleases now that she lives in the south.

"The impulse to punish Ms. Barber in response to what she said in that video is understandable as an emotional reaction," said the letter signed by Ira Glasser, former executive director of the ACLU, Norman Siegel, former director of the New York Civil Liberties Union, and Michael Meyers, the president and executive director of the New York Civil Rights Coalition and former executive committee member of ACLU.

Barber has been the target of outrage and condemnation, even from her own mother, who said the punishment fits the crime.

Bell, the University of Alabama President, made clear that Barber was no longer welcome to attend the university in a statement.

"The actions of this student do not represent the larger student body or the values of our University, and she is no longer enrolled here," Bell wrote. "We hold our students to much higher standards, and we apologize to everyone who has seen the videos and been hurt by this hateful, ignorant and offensive behavior. This is not who we are; it is unacceptable and unwelcome here at UA."

The open letter by the civil rights activists, submitted by New York Civil Rights Coalition, notes that as a public institution, the school is subject to the First Amendment -- whether or not it agrees with the speech.

By outlawing speech some deem offensive, the letter contends, the school opens the door to censoring other, progressive views, as offense lies in the eye of the beholder.

"The first ban on 'offensive' speech is never the last, and the power to ban speech is barred by the First Amendment because it all depends on who is exercising that power, and what he or she finds 'offensive,'" the letter writes argue.

They note that Martin Luther King Jr.'s movement was once considered offensive to many white people, and that silencing it could have had devastating consequences for the civil rights movement.

While organizations like the ACLU are often associated with fighting against racism, homophobia and sexism, they have been known to defend the rights of more controversial groups as well, including white supremacists.

The University of Alabama did not immediately respond to calls and emails seeking comment on the letter Friday morning.

Barber could not be reached by phone Friday morning. Attempts to reach her at addresses associated with her family Thursday were not successful.

Barber told the New York Post Wednesday that she is sorry for her words.

"I did something really, really bad," she said. "I don't know what to do and I feel horrible. I'm wrong and there's just no excuse for what I did. ... I feel so, so bad and I am so sorry."

Amanda Hoover can be reached at ahoover@njadvancemedia.com. Follow her on Twitter @amandahoovernj. Find NJ.com on Facebook.

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