The New Jersey legislative committee investigating the controversial lane closings at the George Washington Bridge authorized 18 new subpoenas Monday, including one seeking records that will show who was aboard state police helicopters during the four days of the closings in September.

The committee also voted that claims last week against self-incrimination by two former aides to Gov. Chris Christie were insufficient and that they must turn over documents related to the closings. Assemblyman John Wisniewski, the Democratic co-leader of the panel, said that the Fifth Amendment protests by Bridget Anne Kelly and Bill Stepien in response to earlier subpoenas “do not pass the scrutiny that is required.”

The committee voted to allow its special counsel, Reid Schar, to establish new dates for them to turn over documents, and to take whatever measures he believes necessary to compel them if they refuse again.

Mr. Stepien’s lawyer, Kevin H. Marino, indicated that he would fight the subpoena in court.

“We have provided the Committee with a detailed explanation of our constitutional and common law objections to the subpoena,” he said in an email. “If the Committee asks a court to enforce that subpoena despite its legal infirmities, we will bring those objections to the court’s attention.”