Van Houten's case is being heard before California's 2nd District Court of Appeal, which will consider whether to overturn a Los Angeles County Superior Court judge's ruling denying parole for Van Houten last year.
Van Houten's attorney, Rich Pfeiffer, will argue that his 69-year-old client deserves to be released because she's a changed woman, takes responsibility for her actions and has been a model inmate for more than four decades. Prosecutors will continue to vigorously fight Van Houten's release because of the seriousness of the crimes.
Van Houten was 19 when she and fellow cult members stabbed Los Angeles grocer Leno LaBianca and his wife Rosemary to death in 1969. The killings took place a day after other so-called Manson family members murdered actress Sharon Tate and four others in crimes that shocked the world.
Van Houten, who is serving life in prison, was only involved in the LaBianca killings. She is not expected to be at Wednesday's hearing.
Every year since 2016, a parole board has recommended that Van Houten deserves to be released, finding that she's no longer a threat to society. Former Gov. Jerry Brown twice blocked Van Houten's release, saying she had failed to explain how she transformed from an upstanding teen to a killer and that she laid too much of the blame on Manson.
The parole board's most recent decision on Jan. 30 is undergoing a five-month review process before heading to Gov. Gavin Newsom's desk.
The 2nd District Court of Appeal's three-judge panel could decide the case following Wednesday's arguments, potentially rendering any decision by Newsom unnecessary, or the judges could decide that the case belongs in the governor's hands.
Pfeiffer said he has never been so optimistic that Van Houten will win.
"This has been the best anything has ever looked since I've been on the case," he said. "This is probably the best way out."
But courts can be reluctant to interfere in matters of parole, said Samuel Pillsbury, a criminal law professor at Loyola Marymount University in Los Angeles.
"It is highly emotional," Pillsbury said. "The voters have decided the governor should have a veto on this so the courts would prefer to let this process play out."
If the decision comes down to the governor, Pillsbury said Van Houten has an uphill battle because of the infamy of the Manson murders.
"The Manson case is one of a kind," he said. "There's no other case like it in terms of the number of people in California who feel strongly about it, who've lived through it. The entire state and much of the nation still feel some degree of trauma from that, and it makes it a very different kind of case from an elected official's point of view."
In denying Van Houten parole last year, Los Angeles Superior Court Judge William Ryan found that she would "pose an unreasonable risk of danger to society," citing the brutal nature of the crimes.
During one of her parole hearings, Van Houten said the murders were the start of what Manson believed was a coming race war that he dubbed "Helter Skelter," after a Beatles song, and that he had the group prepare to fight and learn to can food so they could go underground and live in a hole in the desert.
Van Houten said she was traveling up and down the California coast when acquaintances led her to Manson. She candidly described how she joined several other members of the group in killing the LaBiancas, carving up Leno LaBianca's body and smearing the couple's blood on the walls.
Manson died of natural causes in 2017 at a California hospital while serving a life sentence
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