Federal Judge Amy Berman Jackson on Tuesday rejected former Trump campaign chairman Paul Manafort's attempt to invalidate the criminal case against him in Washington.
Manafort had claimed special counsel Robert Mueller's appointment order was too broad, and thus his investigation had overstepped its legal authority.
But Berman Jackson concluded for several reasons that Mueller's investigation and prosecution of Manafort is legal -- and that the special counsel still can maintain some independence while working within the Department of Justice.
Manafort has pleaded not guilty to charges related to his lobbying work for Ukrainian politicians dating back to a decade ago.
"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. But the indictment will not be dismissed, and the matter will proceed to trial," Berman Jackson wrote in her opinion Tuesday.
She added that it was appropriate for federal investigators to look into Manafort's business connections in Russia and Ukraine while Mueller's office investigated possible coordination between the Trump campaign and the Russian government.
"Who had connections to the Russian government? Who attended meetings on behalf of the campaign?" Berman Jackson wrote. "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 Special Counsel would have been remiss to ignore such an obvious potential link between the Trump campaign and the Russian government," she wrote later in the opinion.
Jason Maloni, a spokesman for Manafort, later responded to the ruling: "Paul Manafort maintains his innocence and looks forward to prevailing in this matter."
Manafort is scheduled for trial in DC in September.
He faces a separate set of bank fraud and other financial charges in Virginia, for a trial set to begin in July. Manafort has asked a different federal judge there to dismiss his case on similar grounds. The Virginia federal judge, TS Ellis, has not yet ruled on the question. Ellis expressed his skepticism at a previous hearing that Mueller's current investigation into Russian coordination during the 2016 campaign would connect to Manafort's lobbying activities years before the Trump campaign existed.
Berman Jackson previously dismissed a civil lawsuit Manafort had attempted to use to undercut Mueller's authority.