The man behind crypto exchange FTX, which collapsed last year, has filed motions to dismiss 13 charges of fraud against him.
Lawyers for Sam Bankman-Fried, 31, said the US government failed to properly explain what offences he is alleged to have committed.
They tried to persuade the judge to dismiss most of the charges against him, which include fraud and bribery.
Bankman-Fried has already denied the charges.
The case against Bankman-Fried is that he stole customer deposits to pay for risky “bets” on his hedge fund, Alameda Research.
He is also alleged to offered money to American politicians.
FTX was reported to have 80,000 UK customers, most of whom will have lost heavily when the company crashed last November.
The crypto exchange was high profile and was well-regarded in financial circles before its bankruptcy.
The US authorities have a fortnight to respond to the motions filed on Monday (May 8) with the next official hearing on June 15.
Bankman-Fried is under house arrest on a $250 million bond at his parents’ home in Palo Alto, California.
The accused admits mishandling his business but denied fraud.
Three of Bankman-Fried’s former business partners — Gary Wang, Caroline Ellison and Nishad Singh — have pleaded guilty to numerous charges and are cooperating with investigators.