The organization filed the action with a private dispute resolution entity over the former Miss Pennsylvania USA's claim that another contestant spotted the list of finalists on a planning sheet hours before the event was held Sunday, outside counsel Scott Balber said.
A statement from the New York-based Miss Universe Organization said it is seeking remedies including monetary damages for her "ongoing defamatory statements." Balber would not say how much money organizers are seeking.
The pageant also released a statement from Miss Florida USA - the contestant Sheena Monnin claims saw the list - in which she disputes Miss Pennsylvania's version of the events that prompted her to step down.
Monnin gave up her crown Monday, claiming in a Facebook post that the pageant had been rigged, with the top five finishers selected before the show was broadcast Sunday night from Las Vegas. Pageant organizers immediately denied Monnin's allegation and claimed she had actually stepped down because she disagreed with the pageant's decision to allow transgender contestants.
Earlier Friday, Monnin told NBC's "Today" show that she was standing by her claim that Miss Florida USA confided in her that she'd seen a list of finalists Sunday morning.
"I know what I heard, and I know what I in turn witnessed come true based on what the contestant said she saw," Monnin said.
Monnin claimed Miss Florida USA Karina Brez named the top five contestants in the same order they were called during the broadcast.
"That's just too coincidental to not be true," she said.
But a statement released Friday by Brez disputes Monnin's account, saying Brez was only making a joke about a list of contestants that she saw.
"The list I saw didn't even have the eventual winner on it," the statement read.
This year's Miss USA winner was Olivia Culpo of Rhode Island.
Pageant officials maintain the judging was done fairly and under the watchful eye of auditor Ernst & Young.
"(The) tabulation of the judges' votes which determined the final five contestants did not occur until after the evening gown competition had been completed," Ernst & Young said in a statement released Friday evening.
A group of preliminary judges selects 15 top contestants before the telecast along with a 16th picked by fan vote. Those contestants are then whittled down by the telecast judges, who this year included celebrity chef Cat Cora and Arsenio Hall.
Monnin does not have a listed phone number and did not respond to Facebook messages seeking comment. Attorneys for the pageant said they forwarded her the arbitration action directly because they did not know whether she'd retained a lawyer.
Balber said the action filed with the private arbitration company is confidential under the terms of the contestant contract, but that Monnin could release it if she wished.
Earlier this week, pageant organizers released the text of Monnin's resignation email; it doesn't specifically mention rigging, but does mention organizers' decision to allow transgender contestants into the competition.
In the "Today" interview, Monnin did not deny the transgender contestant issue played a role in her resignation.
"There are a myriad of reasons why I'm resigning," Monnin said. She went on to point out that same email mentioned "fair play," but didn't elaborate what she meant at the time.