Fired Christie staffer Bridget Kelly and two-time campaign manager Bill Stepien say complying with the subpoenas carries the risk of self-incrimination.
Kelly, wearing a fuchsia coat, did not speak to the reporters who surrounded her when she arrived at the courthouse Tuesday. Stepien was not expected to attend.
The subpoenas seek documents involving the intentional blocking of traffic near the George Washington Bridge in September, which created hourslong backups in nearby Fort Lee, apparently to punish the town's Democratic mayor.
A parallel criminal investigation by the U.S. attorney's office seeks to uncover whether federal laws were broken. The legislative panel wants to find out how high up Christie's chain of command the lane-closing scheme went and why it was hatched.
Christie, whose viability as a 2016 Republican presidential candidate has been called into question since the scandal erupted, has said he knew nothing of the plot's planning or execution. He said in December that no one on his staff was involved, a statement he was forced to retract in January when private emails showed otherwise. An email from Kelly saying "time for some traffic problems in Fort Lee" appeared to set the scheme in motion.
The reply, "got it," from a Christie loyalist at the Port Authority of New York and New Jersey, the agency that runs the bridge, implies a prior conversation about the lane closings occurred.
In all, five people close to Christie have been fired or resigned. Some 32 people or organizations close to the governor, including his re-election campaign and Republican State Committee, have been subpoenaed. All but Kelly and Stepien have complied or are in the process of producing documents.
Kelly and Stepien are attempting to invoke their Fifth Amendment right against self-incrimination. They argue that the subpoenas are overly broad and require them to make judgments about which documents involve the lane closings.
"I'm not saying they are using any thumbscrews or not being held on a rack, but they are basically requiring us to incriminate ourselves by asking us to turn over these type of documents," said Kelly's attorney Michael Critchley.
"I feel very strongly that Bill Stepien is an innocent man, an innocent man who has been ensnared by ambiguous circumstances and someone who has every much the same right to express his Fifth Amendment privilege," said Kevin Marino, Stepien's attorney.
Lawyers for the legislative panel say the two are not entitled to blanket protection from the subpoenas and have not produced sufficient evidence to back up their fear of prosecution claim.
Stepien's lawyer said FBI agents visited his client's apartment and inquired whether he paid the rent on time; Kelly's lawyer said agents sought to interview his client and her parents, but that no one was willing to talk.