Berman Jackson previously dismissed a civil lawsuit Manafort had attempted to use to undercut Mueller's authority. Much of her opinion tracks ThinkProgress' analysis from last January, explaining why Manafort's arguments were unlikely to prevail. The memo, which came months before Manafort's indictment, shows Rosenstein specifically authorized Mueller to investigate Manafort's Ukrainian work and related financial crimes.
Beyond investigating links between Russian Federation and Trump's campaign, Mueller is also charged with pursuing "any matter that arose or may arise directly" from his collusion probe.
"Given the combination of his prominence within the campaign and his ties to Ukrainian officials supported by and operating out of Russia, as well as to Russian oligarchs, Manafort was an obvious person of interest", the ruling said.
Jackson ordered that Robert Mueller's authority under the special counsel guidelines is wide enough to cover investigation of Manafort, given he was Trump's campaign chairman. So Manafort has no right to challenge an alleged violation of those regulations.
"First, the indictment falls squarely within that portion of the authority granted to the Special Counsel that Manafort finds unobjectionable: the order to investigate 'any links and/or coordination between the Russian government and individuals associated with the campaign, '" she continued.
Finally, Mueller was appointed "to take over an existing investigation".
"When it promulgated the regulations, the department anticipated that a special counsel, like any other prosecutor, could become aware of, and could have legitimate reasons to explore, paths that branch out naturally from the original investigation, as well as entirely new and disconnected allegations", Jackson wrote.
"It bears emphasizing at this stage that Manafort is presumed to be innocent of these charges, and it will be the prosecution's burden to prove him guilty beyond a reasonable doubt".
Prosecutors also gave the judge a secret filing with additional information about one of the articles cited by Manafort, but didn't specify which article or why it needed to be withheld from Manafort's defense. His lawyers filed for a dismissal on the basis that the charges extended beyond the scope of Mueller's appointment.