The federal government won’t fine United Airlines for the forcible removal of a ticketed passenger from an overbooked flight last April, an incident that prompted the carrier to implement a slew of policy changes.

That’s according to a May 12 letter from the Department of Transportation to United [PDF] — which passenger advocacy group Flyers Rights obtained through a Freedom of Information Act request. In the letter, the agency said its investigation of the April 9 incident focused on whether United complied with the DOT’s oversales rule and federal anti-discrimination statutes.

The investigation

“Based on the information we gathered during our investigation, we find that that United complied with some, but not all, of the requirements of the Department’s oversales rule,” the letter reads.

The agency’s review of United’s boarding policies, its internal manuals and reference guides, passenger records, and statements from airline employees “indicated that United properly established and used non-discriminatory criteria to select passengers who were involuntarily denied boarding.”

“There was no evidence that United discriminated against any of the passengers who were involuntarily denied boarding on Flight 3411 based on their race, color, national origin, religion, sex, or ancestry,” the DOT says in its letter.

And while the agency noted that United hadn’t provided Dr. David Dao and his wife with a written copy of federal rules on what airlines can do when flights are overbooked, the agency said the carrier only failed to do so because the couple quickly left to take the injured Dao to the hospital.

RELATED: Airline Complaints Soar Following United’s Forced Removal Of Passenger

However, the DOT says it was “unable to determine” whether United had complied with the requirement in the oversales rule to involuntarily bump passengers only if an insufficient number of volunteers come forward.

While it’s “undisputed that United sought volunteers willing to give up their seats for compensation several times,” there is “conflicting information” regarding whether United had then offered Dao and his wife the chance for one of them to stay on the flight.

“The written statements from different individuals who are material to our investigation are in substantial conflict and in our view the conflict is unresolvable,” the DOT writes.

Although the DOT says it found United hadn’t provided the correct compensation to one of the five passengers who were bumped involuntarily from that flight, the airline sent the rest of the money 10 days later.

“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 agency said. “Therefore, we conclude that enforcement action is not warranted in this matter.”

Not included in the investigation was the conduct of the three Chicago airport police officers who pulled Dao out of his seat after he refused to leave the plane.

United responds

“This incident should never have happened and we are implementing all of the improvements we announced in April, which put the customer at the center of everything we do,” United said in a statement, noting that while it still has work to do, it’s made “meaningful strides” that improve the customer experience.

The president of Flyers Rights, Paul Hudson, called the removal of Dao “egregious in every sense of the word.”

“For the Department of Transportation to conclude that United Airlines’ conduct did not warrant an enforcement action is a dereliction of duty,” he said in a statement.

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