A federal judge raised doubts Thursday about the scope of the order used to appoint special counsel Robert Mueller to probe alleged collusion between the Trump campaign and Russia.

During a two-and-a-half hour hearing in one of Mueller’s criminal cases against former Trump campaign chairman Paul Manafort, U.S. District Judge Amy Berman Jackson questioned whether Deputy Attorney General Rod Rosenstein’s directive appointing Mueller granted him more authority than Justice Department regulations appear to permit.

Manafort’s lead defense attorney, Kevin Downing, noted that the May 17 order appointing Mueller grants him authority to pursue the Trump-Russia probe as well as other issues that “may arise” from that investigation. Downing said that was at odds with Justice’s rules, which say a special counsel must be told of the “specific factual matter” in his or her mandate.

“That’s a fair point,” Jackson said, adding later: “I don’t think that, as good as he is, that the deputy attorney general can see into the future.”

However, it’s far from clear whether whatever doubts Jackson may have about the appointment order will actually benefit Manafort in the criminal cases he currently faces: a five-count indictment in Washington on charges of money laundering and failing to register as a foreign agent for Ukraine and an 18-count indictment in Virginia on charges of bank fraud, tax evasion and failing to report foreign bank accounts.

Manafort’s lawyers have argued that Rosenstein’s May 17 order exceeded his authority under regulations adopted two decades ago to replace an expired and much-criticized independent counsel law. Manafort’s defense also contends that Mueller has gone further than Rosenstein authorized.

Mueller’s team argued Thursday that criminal defendants and the public at large have no right to enforce those regulations. Manafort’s attorneys insist he can use violations of those rules to challenge the legitimacy of the indictment, but Jackson gave little indication Thursday that she agrees with them.

“It’s all happening within the Executive Branch,” Jackson noted. “I want to know if these [regulations] are actionable at all.”

Downing insisted that if there were flaws in Mueller’s appointment, it undermines his legal authority to bring the cases he’s filed.

“I don’t know how they can violate these regulations and we can still be here and it doesn’t matter,” the defense attorney said. “It doesn’t make any sense.”

A senior Justice Department attorney working with Mueller's office, Michael Dreeben, defended Rosenstein's order and insisted that it clearly gave Mueller the authority to investigate and charge Manafort for his Ukraine-related business dealings.

"It's not a blank check. It's not carte blanche," Dreeben said of the appointment order.

Earlier this month, Justice Department lawyers gave the court a copy of a memo Rosenstein wrote last August detailing the scope of Mueller's authority. It revealed that Mueller was specifically authorized by Rosenstein to investigate and prosecute crimes related to Manafort's receipt of payments from the Ukrainian government.

Dreeben insisted Thursday that was not an expansion of Mueller's authority, but a description of what was originally in it.

"That order reflects confirmation of what was within our scope at the time of our appointment," he said. "It's not an after-the-fact justification order."

That issue could be significant because while Manafort's initial indictment last October came well after the August memo, ..read more at Politico