Her Book Described Bringing Bill Cosby to Justice. Then He Was Freed.

Andrea Constand was taking what she has described as a step toward healing: 16 years after naming Bill Cosby in a lawsuit as the man who had sexually assaulted her, and three years after he was convicted and sentenced to prison for the crime, she was ready to tell her story in a memoir that is due to be published in September.

The forthcoming book traces Ms. Constand’s journey from disbelieved accuser to a powerful voice in the #MeToo movement, one of dozens of women who came forward with similar accounts of abuse and misconduct by Mr. Cosby but the one who, in the words of her publisher, had “the power to bring him to justice.”

But instead of having the last word, a key part of Ms. Constand’s narrative — if not her book — was rewritten Wednesday when the Pennsylvania Supreme Court freed Mr. Cosby on procedural grounds. The court did not exonerate Mr. Cosby, 83, but said that he should not have been charged because a previous district attorney had given him assurances that he would not be prosecuted.

The court’s decision was “disappointing,” Ms. Constand and her lawyers said in a statement, which noted that they had not been consulted on, or even been made aware of, the closed-door prosecutorial maneuverings more than a decade ago that eventually allowed Mr. Cosby to walk out of a maximum-security prison near Philadelphia on Wednesday. And in a case once seen as a harbinger of women’s right to justice, the effect, Ms. Constand and her lawyers feared, would be to once again silence victims of assault.

For other women who said that they had survived assaults or misconduct by Mr. Cosby — more than 50 have come forward — the whiplash was intense, especially for those who gave corroborating accounts in his criminal trial.

“We know he’s guilty, but as far as I’m concerned, as of today, the justices that have made this decision have just enabled a criminal to go without a consequence,” Heidi Thomas, who testified that Mr. Cosby raped her in 1984, told a Denver news channel. “What message is that sending to other victims? To other perpetrators? This is one case, but the precedent they have just set is devastating.”

Ms. Constand, 48, who is now a licensed massage therapist in her native Canada, has movingly described how much the Cosby case upended her life; she called her memoir “The Moment,” as in, the moment everything changed.

“I’m a middle-aged woman who’s been stuck in a holding pattern for most of her adult life, unable to heal fully or to move forward,” she said in her victim impact statement before Mr. Cosby’s sentencing in 2018, describing the rippling aftereffects of the night when she said he drugged and violated her in his suburban Philadelphia mansion.

At the time, in 2004, she was a 30-year-old director of operations with the Temple University women’s basketball team, and she considered Mr. Cosby, then 66, a grandfather-like friend and mentor. Their encounter — when she was literally immobilized by the pills Mr. Cosby gave her, according to her testimony — was a profound betrayal, she said.

“Bill Cosby took my beautiful, healthy young spirit and crushed it,” she said in her statement to the court. “He robbed me of my health and vitality, my open nature, and my trust in myself and others.”

According to several published excerpts, her book, to be released by Viking Canada, describes her history as a confident, athletic youth from Toronto turned professional basketball player in Europe, who initially connected with Mr. Cosby, a Temple alumnus and donor, over sports.

Recounting the assault, first to the police and prosecutors a year after she experienced it and then in a civil suit and two criminal trials, was re-traumatizing, she has said. Lawyers for Mr. Cosby sought to portray the interaction as consensual.

“The attacks on my character continued, spilling over outside the courtroom steps, attempting to discredit me and cast me in false light,” she said in her statement to the court in 2018. “These character assassinations have caused me to suffer insurmountable stress and anxiety, which I still experience today.”

Writing the memoir was meant to be an act of closure — a long-delayed one. “I did not want to lose any memories to time, and believe that reflection is a necessary final step toward true healing,” she said in an interview with her publisher, according to CBC Books. “By sharing stories, we can begin to help those whose lives have been impacted by sexual violence.”

Neither Ms. Constand nor a representative for Viking Canada responded to requests for comment about the status of the book.

In an excerpt that was published last month in Elle, Ms. Constand describes the moment in 2005 when she learned that Bruce L. Castor Jr., who was then the district attorney in Montgomery County, Pa., outside Philadelphia, had decided not to move forward with her case.

“It was yet another sharp blow in what had already been, without a doubt, the most difficult year of my life,” she wrote.

It was a decision that would have unanticipated ramifications this year.

Mr. Castor — who earlier this year was one of the lawyers representing President Donald J. Trump’s in his second impeachment trial — announced in a news release at the time that his investigation had found “insufficient” evidence to proceed with the case. He has since said that he assured Mr. Cosby that he would not be prosecuted to pave the way for Mr. Cosby to testify in Ms. Constand’s civil case. In depositions for the civil case, Mr. Cosby acknowledged giving quaaludes to women he was pursuing for sex.

When the civil case was settled in 2006 for $3.38 million, Ms. Constand later said, she believed that “this awful chapter in my life was over at last.”

But when a new district attorney decided to pursue the charges that Mr. Castor had not, Ms. Constand agreed to once again put herself on the stand, though she was shamed and exhausted by the process, she has said.

It ended with his conviction in 2018, a moment that was hailed at the time as a sign that in the #MeToo era the accounts of women would be given more credence.

Though her story now has an unwelcome coda, Ms. Constand appears unbowed. On Thursday, she retweeted a message from Hope, Healing and Transformation, a foundation she started last year to offer guidance and support to survivors, which will receive a portion of the proceeds from her memoir. “Your story and voice matter right now more than ever. Silence is NOT an option. BILL COSBY IS NOT INNOCENT.”