Paul Manafort, best known for his short-lived stint as the campaign manager for then-presidential candidate Donald Trump, filed a lawsuit in a US District Court in Washington on Wednesday against the Department of Justice and Robert Mueller.

The suit comes less than three months after Mueller—appointed last May to lead an investigation into the relationship between the Trump campaign and Russian officials—indicted Manafort and business associate Rick Gates on charges of money laundering, among other crimes (like “conceal[ing] from the United States their work as agents of...Ukraine and its political parties and leaders”).

Manafort’s suit challenges what he refers to as the “arbitrary” and “capricious” actions Mueller has taken in during the course of his inquiry, arguing that, because the crimes he’s been charged with (and to which he has pleaded not guilty) fall outside the scope of Mueller’s investigation, the Department of Justice should dismiss those charges. This is despite the fact that the order appointing Mueller to his current post states that Mueller may investigate “any matters that arose or may arise directly from the investigation.”

Manafort’s trial, meanwhile, is scheduled to begin in May.