Stepien and another former Christie adviser, Bridget Anne Kelly, have invoked their Fifth Amendment rights against self-incrimination in declining to turn over documents about the lane closures.
In another brief filed Friday, Kelly's attorney argued that the panel had the power to grant her immunity in exchange for compliance with the subpoena.
Stepien says the e-mails provided to the court offer no proof that he even has documents regarding the lane closures - a requirement, he says, for enforcing the subpoena. Of the roughly 30,000 documents the committee has obtained via subpoena, the filing says, it was able to produce only 12 communications involving Stepien.
None of the documents shows Stepien "had any involvement in the decision to close the lanes or to conceal the reasons for the lane closures," Marino wrote.
"Frustrated in its attempt to gather such proofs and faced with the inevitable rejection of its invalid subpoena - and with it, the misguided notion that the lane closure controversy was some sort of high level Christie campaign conspiracy - the committee apparently hopes the court will treat Mr. Stepien's unremarkable e-mail communications regarding the lane closures and the ensuing press coverage as a substitute for such evidence," Marino wrote in Friday's filing.
"It won't work."
In response to a request by Judge Mary C. Jacobson, the committee said in its filing Monday that it did not have the power to grant immunity in exchange for production of documents or to enforce the subpoena through contempt charges. In any case, the committee said, these issues were irrelevant to whether the Fifth Amendment protection applied to Stepien and Kelly.
Marino and Kelly's attorney, Michael Critchley, disagreed with the committee and said it did have those powers.
Critchley suggested the committee wouldn't recognize its own authority to grant immunity because it feared "the U.S. Attorney's Office may intervene and terminate this legislative inquiry."
Both lawyers noted that the Assembly Transportation Committee - which had been investigating the lane closures last year before the Legislature created a new, special committee - had held former Port Authority official David Wildstein in contempt and referred charges to the Mercer County Prosecutor's Office.
The lawyers also said e-mails produced by the committee did not establish that their clients had any documents about the lane closures.
One e-mail shows that Stepien referred to Fort Lee Mayor Mark Sokolich as an "idiot." Some have speculated that Christie allies carried out the traffic jams to punish the mayor for not endorsing Christie's reelection. The governor cut ties with Stepien when that e-mail surfaced in January.
Christie also fired Kelly, his deputy chief of staff, after legislators released an e-mail in which she called for "traffic problems in Fort Lee."
Another e-mail showed that another Christie ally had forwarded Stepien a letter of complaint from Sokolich about the lane closures.
It made sense for the campaign manager to be copied on such an e-mail, Marino wrote, given the potential "public-relations ramifications for the campaign."
It was also "unsurprising," Marino wrote, that Stepien would be consulted on press inquiries in the weeks leading up to the November election.
Marino said the committee violated the law by providing the e-mails to the court. The committee's outside counsel, Reid Schar, said during oral arguments earlier this month that he had more documents showing Stepien's involvement. Marino then asked Schar to provide those documents to him, not to the court or the press.
"Clearly, the committee included the new documents with its submission in an attempt to enlarge Mr. Stepien's role in this affair and improperly influence the court's ruling," Marino wrote.