Special Counsel David Weiss is asking a California judge to exclude any mention of Hunter Biden’s psychological trauma and his resulting years-long addiction to crack cocaine and alcohol from the upcoming tax evasion trial at Los Angeles.

Biden and his attorneys have been asking that addiction experts come to speak about the mental health issues that led him to not pay his hefty tax bills.

For weeks leading up to the trial — which is slated to begin September 9 — Biden’s attorney and Mr. Weiss’s prosecutors have been filing competing motions on evidence and testimony admissions. The prosecution wants to draw a simple line from spending on drugs and personal expenses to failing to pay his taxes because of his indulgent lifestyle. 

In a court filing sent to Judge Mark Scarsi, Mr. Weiss’s lead prosecutors — Leo Wise and Derek Hines — say that defense should not be allowed to mention what could be considered sob stories about Biden’s partying. 

“Nowhere … does he argue that the government’s evidence of the defendant’s partying and drug use while incurring expenses that he later falsely claimed as ‘business’ expenses is inadmissible,” Messrs. Wise and Hines write. “Instead, he argues that the psychological origins of the defendant’s dependency will help de- stigmatize him and asks the Court to adopt an incorrect reading of the ‘rule of completeness’ that would allow him to circumvent the prohibition against hearsay.”

Prosecutors are worried that the defense will paint a broad picture of Biden’s life as a tragic story, from his mother’s and sister’s deaths in a car crash in 1972 to his elder brother’s death from brain cancer in 2015. 

“An opening statement regarding an incident that occurred when the defendant was a toddler which the defense claims caused his addiction more than four decades later would be wholly inappropriate because (as in the firearms trial in Delaware earlier this summer), no witness could testify to it,” the prosecution writes. 

Messrs. Wise and Hines complain vociferously in the filing that Biden’s attorney, Abbe Lowell, had made mention of Biden’s traumatic background in both opening and closing statements at his recent Delaware firearms trial — facts that the presiding judge ruled were irrelevant to the case. 

“The bell simply cannot be un-rung. Defense counsel chose not to introduce any personal history evidence (let alone addiction causation evidence), for instance by not calling James Biden, despite representing he would do so. Indeed, James Biden was sitting in the courtroom during the defense case, but defense counsel never called him,” the prosecutors write of their successful effort to convict the first son. 

“Defense counsel also referenced events in his opening that could never be introduced in evidence, such as the ‘fact’ that the auto accident that killed the defendant’s mother caused his drug use four decades later,” they added. 

Defense counsel has been trying, in several court filings, to get the judge to allow testimony from Biden’s own psychologist, Joshua Lee. They say that only Dr. Lee can testify to Biden’s “diminished” mental capacities at the time he was failing to pay his taxes due to his addictions. 

The government is planning to call multiple witnesses from Biden’s personal and professional life who will testify to his lucrative business dealings and his troubles at home. Biden’s sister-in-law and ex-girlfriend, Hallie Biden, has been offered immunity to speak about Biden’s addiction and finance troubles in the 2010s. 

He has been charged with dodging a $1.2 million tax bill between the years 2016 and 2019. Ms. Biden’s sister, Elizabeth Secundy, who was paid by Biden for unknown business services, has also been offered immunity to testify. 

Another individual, named only as “Business Associate 1” in court filings, will testify about Biden’s overseas business dealings — specifically his work to quash the investigation of a Romanian businessman named only as “G.P.” with the court. 

“G.P. was a Romanian businessman who was under criminal investigation in Romania,” the prosecutors wrote in a court filing. “G.P. sought to retain Business Associate 1, the defendant, and Business Associate 2, to attempt to influence U.S. government agencies to investigate the Romanian criminal investigation of G.P, and thereby cause an end to the investigation of G.P. in Romania.” Messrs. Wise and Hines say that Biden and two other associates split a $3 million payment from “G.P.” for their work, and tried to keep it out of the press for fear of damaging President Biden. 

According to the indictment, Biden’s gross income was nearly $8 million between 2016 and 2019 — all while noting to associates that he was behind on his bills. 

He spent more than half of that money on personal expenses, including more than $1.5 million in cash withdrawals at a time when he was crippled by a severe drug addiction. He also spent nearly $700,000 on payments to “various women,” $400,000 on clothing and accessories, and $300,000 on his children’s tuition. Mr. Biden dispersed more than $70,000 for rehabilitation and nearly $200,000 on “adult entertainment.”

If convicted, he faces up to 17 years in federal prison and a hefty fine.