Normally a firm of McKinsey’s size would swat away a gadfly’s attacks. But in this case, which involves the bankruptcy of Colorado’s Westmoreland Coal, Mr. Alix has a powerful ally: the United States Justice Department. On Dec. 14, the department said in a court filing that McKinsey was fraught with “pervasive disclosure deficiencies” and should be dismissed from the Westmoreland case immediately and stripped of the fees it had earned so far.

If that were to happen, it would deal a severe blow to McKinsey’s reputation, as well as its argument that the firm is free of conflicts of interest.

The judge overseeing the Westmoreland bankruptcy case, David R. Jones, warned both sides in a hearing this month about the rising stakes. “The way this has been teed up, I don’t see an out for both sides,” said Judge Jones, the chief judge of the United States Bankruptcy Court of the Southern District of Texas. “The harder you push all this, the more you ensure that someone doesn’t survive.”

Westmoreland had been sprinting through a bankruptcy process that started in October and was on track to be wrapped up in February. But then Mr. Alix filed a 163-page objection, accusing the prestigious consulting firm not just of hidden conflicts of interest, but of crimes including fraud — “all sorts of heinous acts,” as Judge Jones put it.

Westmoreland asked Judge Jones to overrule Mr. Alix’s objection, but he said he couldn’t do that.

“I don’t like someone to stand up in my court and accuse someone of committing a crime,” he said. “There has to be an airing of this issue, given what’s been done.”