The Ministry of Justice said it is reviewing the decision. Boeing had no immediate comment.
In his ruling, Judge O’Connor said the government’s oversight of the firm in previous years had been “failed”.
“At this point, the public interest requires judicial intervention,” he wrote.
He said the proposed agreement does not require Boeing to comply with the watchdog’s recommendations and gives the company a say in selecting a candidate.
These questions were also raised by some families of those who died during flights, who criticized it as a “sweetheart” arrangement that did not hold the firm accountable for the deaths.
Judge O’Connor also focused on the agreement’s requirements to take into account race in the hiring of the monitor, which he said would undermine the credibility of the selection process.
He said he was concerned about the “changing and conflicting interpretations of how the diversity and inclusion clause of the plea agreement will … work.”
“In a case of this magnitude, it is in the paramount interest of justice that the public be assured that this selection of a monitor is made solely on the basis of competence,” he wrote.
“The DEI parties’ efforts only undermine that trust in the government and Boeing’s ethics and anti-fraud efforts.”
Ike and Susan Riffel of California, who lost their two sons, Melvin and Bennett, said the judge did the “right thing” in rejecting the proposed settlement.
“This deal held no one accountable for the deaths of 346 people and did nothing to protect the airmen,” they said , externalin a statement provided by their attorney.
They said they hoped the ruling would pave the way for “real justice.”