Diddy's claims of 'diminished' mental capacity take center stage days before sex trafficking trial

"The noticed testimony relates to the defendant's diminished capacity to form the mens rea required to commit the charged offenses - in other words, a 'mental condition bearing on the issue of guilt,'" the government wrote in court documents filed Sunday and obtained by Fox News Digital.

Diddy's legal team had to file notice by the deadline in order to introduce "evidence of the effects of drugs and alcohol on [his] memory or cognitive function," according to prosecutors.

Even if the defense had provided notice in a timely manner, the prosecution claimed Dr. Aoun's testimony was "running afoul of the Insanity Defense Reform Act of 1985" and should be deemed "irrelevant, prejudicial, and impermissible under the Rules of Evidence."

While specific details of Dr. Aoun's testimony were redacted from the filing, it seems expert opinion was to be given to support whether Diddy had been "lucid" during the alleged sex-trafficking scheme.

However, the prosecution claimed Dr. Aoun hadn't examined the music mogul. The government argued the expert would be used as a "substitute to calling witnesses," deeming Dr. Aoun's proposed testimony as "impermissible hearsay."

Judge Arun Subramanian ruled to allow Diddy's legal team to use a "swingers" defense during a hearing Friday.

"There's a lifestyle, call it swingers or whatever you will, that he thought was appropriate because it was common," Marc Agnifilo said at Friday's hearing.

"Many people think it's appropriate because it's common."

The federal judge noted Combs' team could not name other high-profile individuals who engage in the "lifestyle" as an example.

He was originally charged with racketeering conspiracy; sex trafficking by force, fraud or coercion; and transportation to engage in prostitution in a federal indictment unsealed Sept. 17. Diddy has maintained his innocence.

Diddy's trial is set to begin on May 5.