Donald Sterling's lawyer has asked that the start of the trial that will decide whether to approve the $2 billion sale of the Los Angeles Clippers to former Microsoft CEO Steve Ballmer be postponed so he can bring in a neurologist who will tell the judge Sterling is not mentally incapacitated.

Bobby Samini told ESPN.com as he left the courthouse Monday that he hoped the trial would be delayed until late July to accommodate the expert witness.

"The reason the doctor is important is he's probably one of the top in his field, and this is a pretty serious situation," Samini told ESPN.com's Ramona Shelburne. "We'd like to make sure we have our expert of choice."

The NBA Board of Governors is set to meet July 15. A delay in the trial would keep them from voting to approve Ballmer as owner of the Clippers. While a vote to approve Ballmer could be taken over a conference call, the board does need to meet with the prospective owner in person as part of the transfer-of-ownership process.

In court documents, Sterling states Dr. Jeffrey Cummings, director of the Cleveland Clinic Lou Ruvo Center for Brain Health, will vouch for him but will be out of town and unable to testify in court until after July 20.

The court filing asserts that if Sterling is not allowed to use Cummings to prove his mental competency, he will risk "grave and irreparable injury insofar as his defense will be impaired and his assets will be subject to distribution without his consent."

On Monday, Judge Michael Levanas also asked lawyers for more legal documents arguing their points before he decides whether to approve the $2 billion sale. The judge said the Sterling Family Trust, which owns the Clippers, does not allow the mercurial billionaire to contest medical findings that are sufficient to remove him as a trustee. But he agreed to consider arguments at a hearing June 30 before a scheduled July 7 trial.

"As I sit here right now, I don't see how this document is ambiguous and you are going to go behind it" to have a full hearing into Sterling's mental competency, Levanas told the lawyers Monday, according to the Los Angeles Times.

It was an encouraging day in court for Shelly Sterling, Donald's estranged wife, as the judge said the provision in the trust was written to allow disqualification of a trustee without having to go to court, according to the Times.

"I don't know why you need a court. Essentially, if a trustee has the power, they have the power," Levanas said. "Why is it you need the court to be involved?"

Samini, Donald Sterling's lawyer, also said the lawyers discussed whether Ballmer, who has agreed to buy the Clippers for $2 billion, had a right to be present during the trial.

Shelly Sterling became the sole trustee of the Sterling Family Trust when two neurologists evaluated Donald Sterling and determined he had a form of dementia consistent with Alzheimer's disease that incapacitated him from making decisions about his business and legal affairs.

Donald Sterling has since challenged that diagnosis and Shelly Sterling's authority to sell the franchise. On June 9, his lawyers filed a motion to revoke the terms of the family trust.

"His state of mind is very sharp," Samini said last week. "He's been undergoing his own tests from his own medical experts, and I can tell you the preliminary findings are quite opposite to what you have seen so far."

According to court records obtained by ESPN.com, the purchase agreement between Ballmer and Shelly Sterling holds that either Donald Sterling must consent to the sale or a court must validate her authority to act as the sole trustee.

Information from ESPN.com's Ramona Shelburne and The Associated Press was used in this report.