Premenstrual dysphoric disorder (PMDD) is a clinical condition that affects women during a specific phase of their menstrual cycle. Considered to be a more severe form of the premenstrual syndrome (PMS), PMDD can cause symptoms of depression, anxiety and irritability, to a debilitating degree. For decades, debate about the disorder has been mired in medical uncertainty and gender politics, meaning that the difficulties faced by PMDD sufferers have tended to be exacerbated by the socio-scientific complexities of their stigmatising premenstrual condition. This changed in 2013, when PMDD was recognised as a medical disorder and included in the DSM 5 as a depressive mental health condition affecting only women. Still the source of a degree of controversy, this new mental health classification acts as the catalyst for this thesis and prompts the question that doubles also as its title: should the premenstrual defendant be held fully responsible for her criminal actions? To answer that question, this thesis tells the story of the premenstrual defendant, as studied through the lens of a feminist legal narrative. Situating the narrative of the premenstrual defendant in its historical and contemporary context, this thesis explores the dynamic, between law, medicine and society at large, that has fundamentally shaped her story. Deconstructing the conceptual master narrative of criminal responsibility, it takes a Laceyan approach to assessing the ideas, interests and institutions that are implicated in the responsibility-attribution processes of the English criminal justice system. Casting a critical eye over the contemporary legal landscape, it also unpicks the construction of the premenstrual defendant as a female character of the criminal law. Drawing on the contextualised narrative of the premenstrual defendant, and bringing the socio-theoretic and normative aspects of her legal story into dialogue with each other, ultimately this thesis proposes a revised model of partial criminal responsibility for the premenstrual defendant. Mitigated criminal liability is recommended as a new hybridised form of partial defence/partial criminal responsibility. In establishing the premenstrual defendant as the paradigmatic model of liability, it is argued that other defendants who currently lack a suitable and socially realistic legal defence might also qualify for this mitigating partial excuse. In this way then, the end of the story for the premenstrual defendant of this thesis becomes the start of a revised story of criminal responsibility-attribution practices more generally.