Marino wrote a letter to Gibson Dunn on April 2 demanding changes to the report, which was released March 27. Gibson Dunn has not addressed those concerns, Marino said, so he released the letter to the media Wednesday.
"The time has come to set the record straight about Bill Stepien," Marino said in a statement accompanying the letter. "He is innocent of any wrongdoing with respect to the Bridgegate affair."
Gibson Dunn attorney Randy Mastro responded in a statement Wednesday, saying the firm declined Marino's request because "based on the evidence, there is no basis for any correction."
"We nevertheless offered Bill Stepien and his lawyer the opportunity to provide us with any evidence they wanted us to consider, but we have received nothing from them," Mastro said. "And self-serving statements by lawyers are not evidence. Hence, our report stands as is."
The disclosure of the letter comes a day after Christie spokesman Michael Drewniak testified before the legislative panel investigating the lane closures that the governor told him Dec. 5, "I always wondered if Stepien knew more about this."
Federal prosecutors also are investigating the lane closures.
Christie cut ties with Stepien Jan. 9, a day after a trove of e-mails about the lane closures surfaced. The governor said at the time he had lost faith in Stepien's judgment.
The Gibson Dunn report says David Wildstein, a former official with the Port Authority of New York and New Jersey, and Bridget Anne Kelly, Christie's former deputy chief of staff, were responsible for the lane closures. It found no evidence of Stepien's participation but described his conduct as "concerning" and "warranting further investigation."
The report says Stepien assured Christie in December he had no prior knowledge of the lane closures, which was "later revealed to be false."
Marino disputed that characterization, noting the report also says Stepien informed Christie on Dec. 12 that Wildstein "would come to [Stepien] with '50 crazy ideas a week,' " and Stepien would direct him to the governor's office.
Marino said "there is no dispute" that the proposed lane-closure idea - which Wildstein described as a traffic study - was one of those ideas Stepien relayed to Christie.
"To state . . . that Mr. Stepien lied to Mr. Christie - a man to whom he was unshakably loyal and unfailingly honest throughout their relationship - is reprehensible regardless of your motive for doing so," the letter said. "It is also actionable."
Marino also demanded that Gibson Dunn correct its "demonstrably false" assertion that an adverse inference could be drawn against Stepien regarding his Fifth Amendment invocation in response to the Legislature.
First, Marino wrote, even when such an inference is permitted in a civil legal proceeding, "the same inference can never be imported into another legal proceeding, let alone to an 'internal investigation.' "
Plus, Stepien didn't invoke his Fifth Amendment right in response to Gibson Dunn's inquiry; he simply declined to speak with the firm, Marino wrote.
The report's mention of an adverse inference "is a transparent and misguided attempt to justify the errant and wrongful termination" of Stepien's consultancy for the Christie-led Republican Governors Association and the "equally unwarranted recision of his nomination to head the New Jersey Republican Party."
By contrast, the report did not say an adverse inference could be drawn from the silence of David Samson, a Christie ally and former chairman of the Port Authority, Marino noted.