A lawyer for a onetime billionaire serving 11 years for insider trading asked a federal appeals court Thursday to toss out the bulk of the evidence in his case and reverse his conviction.

The attorney, Patricia Millett, asked the 2nd U.S. Circuit Court of Appeals in Manhattan to decide that the government acted improperly to persuade a judge in March 2008 to permit a wiretap to be placed on Raj Rajaratnam's cellphone.

The wiretap was used to record 2,200 private conversations by the founder of the Galleon group of 14 hedge funds as he spoke with at least 130 of his colleagues, employees, friends and family.

Millett said the government at Rajaratnam's trial introduced 45 wiretap recordings into evidence, along with extensive evidence derived from the recordings. During its summation, the government repeatedly stressed to the jury that the wiretaps were the "core evidence in this case" for "all the crimes" charged, she noted in court papers before the arguments.

She said the government left vital information out of papers it submitted to get court authority to wiretap Rajaratnam's phone, including information about an extensive probe that began in 2004 into Rajaratnam and his business by the Securities and Exchange Commission. The investigation produced 4 million documents along with numerous witness interviews and a deposition of Rajaratnam.