EXCLUSIVE: In an unprecedented Hollywood union schism, the Motion Picture Editors Guild is demanding an apology and more from IATSE International President Matthew Loeb after an explosive executive board meeting on August 6 that went very bad and seemingly got very personal.

“We have been advised by our client that you have engaged in a number of unprofessional and potentially illegal acts,” said a lawyer for the IATSE Local 700 in a scathing and detailed letter sent today that Deadline has obtained a copy of (see the full letter below). The one-page letter was cc’d to all 13 of the IATSE’s international vice presidents on Wednesday.

“Your public comments – not to mention their sexist undertones – serve not only to undermine Ms. Repola, but also infringe upon her freedom of speech as guaranteed by the Labor Management Reporting and Disclosure Act,” the correspondence detailing remarks allegedly made to and about Editors Guild National Executive Director Cathy Repola by Loeb adds. “Thus all of your comments violate the law.”

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“It was pretty ugly,” an individual who was at the NYC meeting on Monday said of the verbal showdown between Loeb and Repola.

Contacted by Deadline, reps for Loeb said that they had no comment on the letter, which they received today.

The Editors Guild has been very public in recent weeks of its opposition to the new IATSE film and TV contract. Repola, who has called the new deal “a totally unnecessary” and “unacceptable agreement,” is urging her members to vote no on the contract. Her local’s board of directors has also voted unanimously on July 28 to recommend that their members vote against the deal – which has put them at odds with Loeb and the leaders of all the other 12 West Coast studio locals, whose leaders are recommending that their members vote yes.

Funding of the pension plan, Repola told her members, “was addressed to some extent, but in a way that is short-sighted and will undoubtedly leave us fighting in the next round of negotiations and has the studios putting in very little money over the next cycle. There was no additional hourly pension contribution negotiated. A new ‘New Media Residual’ is included, but it is not what the other guilds (DGA, WGA, SAG-AFTRA) received, and it is impossible to put a value on it.”

Repola’s also unhappy that her members only got nine hours of rest between shifts, while the other locals are all getting ten hours. “Some people are saying Local 700 is mad because we got one hour less turnaround than everyone else,” she posted recently online. “The truth is, we are not mad. We think it was wrong. But that speaks to the commitment we all made, the IA and the locals, to not let any one local get singled out.”

Loeb and Repola weren’t always at odds.

At last year’s IATSE convention in Hollywood, Florida, the International President presented her with the “Outstanding Woman Leader Award” in recognition of Repola’s work as chairwoman of the IATSE’s Women’s Committee. On accepting the honor, Repola thanked Loeb and the convention delegates for “a collective effort to embrace all the women of the IATSE.”

That goodwill feels a long time ago now.

Read the full letter from the Editors Guild’s attorneys here: