Andrea Constand was the first to publicly allege, in 2005, that Bill Cosby had sexually assaulted her. The police refused to press charges, citing a lack of evidence. Constand, however, pressed ahead with a civil suit. She was joined by Tamara Green, a lawyer who claimed Cosby drugged and assaulted her in the 1970s, and 13 Jane Doe witnesses, all of whom made similar allegations of assault, being drugged and rape against Cosby. The very same Bill Cosby who played the affable, lovable and infinitely watchable Dr Cliff Huxtable of The Cosby Show.He was television's favourite dad for three decades; the ideal father and moral touchstone on screen and off that many of us grew up with and loved. That global esteem gave Cosby great power and it placed him firmly at the zenith of the firmament of role models. The accusations that started with a trickle became a flood and exposed a Jekyll and Hyde figure: the beloved father in public is revealed as a calculating, serial rapist in private.The allegations were initially dismissed. The weight of disbelief was automatic - not because the facts were not placed before us, but because women's voices are routinely ignored.When a woman says "no" to an assailant she is ignored; when she tells her story in public she is routinely derided, blamed and shamed. We live in a world that does not want to believe that the patriarchal foundations of our families and our society enable the institutionalised abuse of women.mini_story_image_vleft1In the 10 years since Constand came forward, women continued to step out of the shadows to say that they too had been assaulted, drugged and raped by Cosby. This they did despite the public disbelief, despite the fact that Cosby used his considerable power to sue, to settle and to silence.One of the difficult aspects of this case is that many of the alleged crimes cannot be prosecuted because the statute of limitations has passed. Why did it take so long for women to come forward? Patricia Leary Steuer, another of Cosby's victims, has the depressingly simple answer: "In the late '70s, women didn't challenge powerful men."This finally seems to be changing, evidenced by the number of sex-crime cases against celebrities and priests and the valiant attempts to challenge the pervasive rape culture at schools and universities.The women insisting that their long-hidden stories about Cosby's decades of alleged abuse - "a secret tumour" as survivor PJ Masten calls it - formed a wave of anguish, anger and protest that broke with a remarkable feature in New York magazine. The cover depicts 35 of the 46 women who have publicly accused Cosby of assaulting them. In this sombre, iconic image, they resemble the chorus of a Greek tragedy. As Joan Tarshis, another alleged victim, put it, the shared experience of sexual assault has made them a "sorrowful sisterhood".This is a deeply political statement born out of the most intimate of traumas.It might be sorrowful, but it is powerful, this sisterhood, and it is political because this involuntary collective of determined women pose fundamental questions about the nature of patriarchy and gender power.They describe how Cosby has used his status to assault young women since the early 1960s. These survivors' insistence on their right to be heard, and for action to be taken, has finally turned the tide on Cosby.However, his denials, his hubris and his callous dismissal of his alleged victims' experiences are chillingly similar to those of other long-term perpetrators of sexual violence - men like Bob Hewitt in South Africa, and Jimmy Savile, Max Clifford, Rolf Harris and Gary Glitter (to name but a few) in the UK.These women form a powerful chorus. Together, they ensure that they can no longer be dismissed and silenced. "We can't be disappeared," is how Tamara Green put it.mini_story_image_vright2I listened to each of the women's harrowing testimonies of rape and assault. They describe the casual trashing of their bodies, their dignity, their trust, by Cosby, a man they all admired and then feared. One after another they bear witness to their humiliation and violation and to the injustice of a society that would not hear them or that could not listen to them.Listening to these women's accounts, one after the other, one hears the shock, the powerlessness and the fear. Their voices break when they describe the effect these assaults have had on their lives. Many describe being drugged without their knowledge and rendered unconscious. A state in which consent is, of course, impossible.The cumulative litany reads like a decades-long campaign of terror. Rape is, after all, an intimate form of terrorism.You never know where the attack is going to come from and you never know why it happened to you.These allegations reveal Cosby - like so many men in positions of power - to be a patriarch who has abrogated with impunity the rights of women with regard to their bodies.They reveal the gulf between the public face of benign paternalism and the naked remorselessness of patriarchal power that is premised on the impunity that comes with the social silencing of women.The right to public speech - the right to be heard, the right to justice - has been something that women, that feminists, have fought for because it is the defining marker of citizenship.This chorus of accusations insists that women's voices, women's experiences, do have weight and authority. It is a voice that speaks back to Bill Cosby and the men like him.These survivors have had to speak in unison in order to be taken into account, but theirs is not the voice of victimhood. It is a collective voice of refusal and exposure. It has taken decades, but the silence has been broken.Orford is the president of PEN South Africa. Her latest novel is "Water Music"..