Bridget Kelly appeared at the hearing in Trenton, the New York Times reported. Kelly refused to answer questions from the reporters who swarmed around her in her first public appearance since she was fired.
Kelly allegedly played a key role in "Bridgegate," the closing of several access lanes to the George Washington Bridge for four days in September. The action by the Port Authority of New York and New Jersey caused massive traffic jams in Fort Lee and was allegedly carried out by Christie allies as an act of political payback.
Lawyers for Kelly and Bill Stepien, Christie's campaign manager in 2009 and 2013, argued that requiring them to respond to the subpoenas would force them to incriminate themselves. The legislature is seeking emails, text messages and other documents on the lane closings.
The legislature's lawyer argued the subpoenas are narrowly focused.
Superior Court Judge Mary Jacobson delayed issuing a ruling.
Elsewhere, a Fairleigh Dickinson University's PublicMind indicates Christie's approval ratings are continuing to slip, down to 41 percent from 61 percent in November.
"Unfortunately for the governor, the investigation appears to be turning him into a more polarizing figure," poll spokeswoman Kristie Jenkins said. "As recently as late last year, his approval numbers were consistently bigger than his disapproves -- by a pretty big margin -- and more voters liked everything about him than disliked everything about him.
"One of the defining characteristics of the governor that makes him a nationally sought after Republican is his widespread appeal in a Democratic state. Bridgegate continues to erode that asset."
The poll queries 703 voters March 4-9. It had a margin of error of 3.7 percentage points.