This Sunday, April 9, 2017, image made from a video provided by Audra D. Bridges shows a passenger being removed from a United Airlines flight in Chicago. Video of police officers dragging the passenger from an overbooked United Airlines flight sparked an uproar Monday on social media, and a spokesman for the airline insisted that employees had no choice but to contact authorities to remove the man. (Audra D. Bridges via AP)

The federal government will not fine United Airlines in the violent dragging of a passenger off one of its airplanes after the man refused to give up his seat to a crew member in April, according to a letter obtained by an airline passengers’ rights group.

In the letter, dated May 12 and released Wednesday by nonprofit advocacy group Flyers Rights, the U.S. Department of Transportation explains that while United violated some rules concerning overbooking procedures, there was no evidence of race or nationality-based discrimination in the incident, and United hadn’t engaged in a pattern of rule-breaking that would warrant a fine.

The Transportation Department did conclude, however, that United neglected to calculate the appropriate compensation for one of five passengers removed from the flight — the amount and passenger were unspecified — and did not provide the victim, David Dao, and his wife with a copy of the federal rules on overbooking proceedings in accordance with regulations, according to the letter.

“We consider United’s failure to initially calculate the proper [voucher] amount for one passenger and its failure to provide the required written notice to Dr. Dao and his wife to be violations of [DOT’s] oversales rule,” the letter reads.

In the April 9 incident, four crew members needed to board a Louisville-bound flight from Chicago O’Hare International Airport, which was overbooked. A gate agent offered $800 in travel credits in addition to the cost of meals and a hotel stay, but no one came forward. After the agent launched into United’s protocol for involuntarily bumping passengers, one passenger — David Dao — refused. Eventually, aviation security officer pulled Dao from his seat and dragged him down the aisle of the plane as he screamed.

Paul Hudson, president of Flyers Rights said he was dismayed by the Transportation Department’s response to the incident.

“The airlines really have only one regulator — and that’s the DOT,” Hudson said in an interview Wednesday. “In addition to the bumping rule, they’re supposed to enforce and prohibit any unfair or deceptive conduct by airlines.”

Hudson called Dao’s dragging off the airplane “egregious” and said the finding of no action reflected poorly on the DOT.

United faced swift backlash in the incident after Dao, a 69-year-old Kentucky man, suffered a concussion, a broken nose and two missing teeth, among other injuries, after the dragging incient. Passenger footage of the dragging quickly went viral and United’s CEO — a once-celebrated communicator — was forced to apologize after botching the initial response to the violent incident.

In its letter, DOT argued that while United flouted certain regulations, the airline remedied the compensation error 10 days later, and Dao wasn’t properly given written notice of the federal rules because he needed immediate medical care for his injuries.

“We generally pursue enforcement action when a carrier exhibits a pattern or practice of noncompliance with the Department’s consumer protection regulations and Federal anti-discrimination statutes that we enforce,” the letter says. “Here, United’s failure to initially provide the correct … amount to one of the five passengers involuntarily bumped was remedied by the carrier shortly thereafter, and United’s failure to provide the required written notice to Dr. Dao and his wife at the airport was related to Dr. Dao and his wife needing to leave the airport to seek medical care for Dr. Dao. … Therefore, we conclude that enforcement action is not warranted in this matter.”

Hudson argued, however, that DOT’s investigation let United off the hook. In its letter, DOT said enforcement action is warranted if an investigation yields evidence of “egregious conduct” in violation of federal laws or violations. The dragging incident met that standard, Hudson said.

“The video gave … first of all, United, a black eye, secondly it gave U.S. airlines and aviation a black eye, and this finding, I think, gives DOT a black eye,” Hudson said.

DOT did not immediately respond to a request for comment on its decision not to fine United.