The multimillion-dollar, two-year prosecution of Smith's two doctors and Stern resulted in a $100 fine and one year of unsupervised probation for Dr. Khristine Eroshevich.
The charges were pushed two years after Smith's death by then-California Attorney General Jerry Brown, just before he launched his successful run for governor.
"Today, a judge has told him, 'You know, you should've kept your mouth shut to begin with,'" Stern defense lawyer Steve Sadow said. "There wasn't a case here and you shouldn't have brought it."
A third defendant, Dr. Sandeep Kapoor, was acquitted by a jury in October.
Stern, Eroshevich and Kapoor, who are not charged in Smith's February 2007 death, were accused of conspiring to feed the drug addiction of the reality TV star and Playboy model and using false names to obtain the drugs.
Anna Nicole Smith Convictions Tossed
Comments