Lawyers for David Dao filed an emergency request with an Illinois state court on Wednesday to gain access to footage shot on the flight.
Citing the risk of “serious prejudice” to their client, the lawyers want the airline and the City of Chicago, which runs O’Hare International Airport, to preserve surveillance videos, cockpit voice recordings, passenger and crew lists and other materials related to United Flight 3411.
Dao was snatched from the seat he had paid for, and was dragged by his hands on his back off the parked plane, which had been bound for Kentucky.
Dao is scheduled to hold a press conference Thursday morning.
United Chief Executive Officer Oscar Munoz on Wednesday apologized to Dao and said the company would no longer use law enforcement officers to remove passengers from overbooked flights.
Three security officers have been placed on leave after the incident, according to the Chicago Department of Aviation.
Republican and Democratic lawmakers denounced how Dao was treated.
Two online petitions calling for Munoz to step down as CEO had more than 124,000 signatures combined by Wednesday afternoon.
Shares of United Continental (UAL) closed 1.1 percent lower on Wednesday.
Delta Air Lines (DAL) CEO Ed Bastian defended overbooking as “a valid business practice."
As of Tuesday, Dao was still in a Chicago hospital recovering from his injuries.