The subpoena, a copy of which was obtained by The Times, was issued to William Rosenbluth, an expert in black boxes, also known as event data recorders. Rosenbluth obtained the recorder from the family of Christopher Eves, a Washington state man who died after his vehicle struck a tree in 2007.
Investigators found alcohol in Eves' blood, but his father, a former law enforcement official, contends that much about the accident is unknown.
Ron Eves, the victim's father, said he had unsuccessfully attempted to get Toyota to evaluate the data recorder after the accident and that the company had refused until congressional hearings this year, when Sen. Maria Cantwell (D-Wash.) requested the company's assistance in downloading the recorder.
The results, taken by Toyota in early April, indicated that the truck was traveling at roughly 75 mph, but somehow slowed by 177 mph after hitting the tree.
Rosenbluth, who has assisted the Eves family, said the Toyota readout was flawed and incomplete. Ron Eves said he had no intention of suing Toyota, but he was concerned that his son's truck was defective and was trying to learn the truth about the crash.
Clarence Ditlow, executive director of the Center for Auto Safety, made the subpoena available to The Times. He said the subpoena for the recorder was the first by NHTSA in the agency's investigation of sudden acceleration problems in Toyota vehicles.
"It is a little heavy-handed," Ditlow said. "I only wish they were as hard on Toyota as they are on Mr. Rosenbluth."
Rosenbluth could not be reached, but in an e-mail contended that Transportation Department officials said they would not allow him to observe their examination of the recorder. Transportation Department officials did not have an immediate comment on the order.