A Los Angeles judge barred prosecutors from asking a witness whether a sexual relationship existed between celebrity model Anna Nicole Smith and the woman psychiatrist accused of providing her with excessive medication.
Superior Court Judge Robert Perry, who said he wanted to avoid "a circus sideshow", objected when the issue was raised during questioning of Smith's bodyguard.
"What's the relevance?" he asked deputy district attorney Renee Rose.
Ms Rose said it would show motivation for Dr Khristine Eroshevich to grant Smith's demand for increasing amounts of medication.
Search warrants executed in the case and released a few weeks ago described photos of Smith and Eroshevich in a bathtub in a sexual situation.
"This is a preliminary hearing," Judge Perry told the prosecutors. "It's not a trial. It's to determine if there's probable cause for a trial. I'm just not going to turn this into some circus sideshow."
He said the issue could be raised again at trial before another judge, who could then rule on its relevance.
Outside court, lawyer Adam Braun, who represents Eroshevich, called the sexual allegation a distraction and said the judge made the right decision.
Eroshevich, Howard Stern and Dr Sandeep Kapoor are charged with conspiring to illegally provide controlled substances to Smith. All three have pleaded not guilty.
The defendants are not charged with Smith's death at a Florida hotel in 2007, which was ruled an accidental overdose.
In his second day on the witness stand, bodyguard Maurice Brighthaupt said repeatedly that Eroshevich and Stern, who was Smith's boyfriend-lawyer, never meant her any harm and cared deeply about her wellbeing.
Mr Brighthaupt sadi on Wednesday that he saw both Stern and Eroshevich inject Smith with drugs at a time when she was so devastated by the death of her son in 2006 that she was unable to sleep or function and began abusing prescription medications.
But Stern's lawyer, Steve Sadow attacked Mr Brighthaupt's truthfulness under cross-examination yesterday.
Mr Brighthaupt acknowledged accepting payments of £94,000 for interviews with cable TV outlets after Smith's death. Many of the things he said then were lies, crafted to protect her reputation, he said.
Among them were statements that he never saw Smith take illicit drugs and that she was in control of everything, including decisions about her medication.
"I had a lot of time to think about everything I said in the past, and I'm trying to rectify everything now," he said.
Mr Brighthaupt was expected to conclude his testimony today.
Larry Birkhead, the father of Smith's daughter, was ordered by the judge to be ready as the next witness.
Under Ms Rose's questioning, Mr Brighthaupt said that in October 2006, a month after Smith's son died, she went into a swimming pool outside her hotel suite, fell off a float and sank to the bottom. He said he pulled her out and did CPR to revive her.
She was in hospital for two weeks with pneumonia, he said.
Mr Brighthaupt also gave a vivid description of Smith's agonising final days in February 2007, saying she was swigging sleep medication, swallowing prescription drugs and wandering in a dazed state.
The day before she died, Mr Brighthaupt, a paramedic, said Eroshevich and Stern were present with another doctor when Smith, who had a 105-degree (40.5 Celsius) fever, refused to go to hospital because she did not want to encounter any paparazzi.
"I got everyone in the room to agree if we couldn't get her temperature down we would take her to the hospital," Mr Brighthaupt said.
He said the group decided to have him put her in a tub of water and pour ice over her.
"She was crying and begging to come out of the ice water," said Mr Brighthaupt who thought it was the wrong therapy for the condition. Eventually, he said the ice brought her temperature down to 96 or 97.
The following morning, he said, Stern left to look at a boat and Mr Brighthaupt was sent to pick up visitors from the Bahamas. The bodyguard left his wife, a registered nurse, to watch over the sleeping Smith. After a short time, she called him.
"She said, 'Anna's not breathing'," he said, saying he told her to call the emergency services while he rushed back to the suite.
"She looked pale. Her lips were a little blue. When I picked her up she was a dead weight," he recalled. "I didn't find a pulse. She wasn't breathing. I just put her on the floor and began doing CPR."
Paramedics arrived but she never regained a pulse, he said.
During the account, Stern covered his face with his hands in the courtroom.