Historically before the rise of the asylum system in the UK, terms such as ‘madness’ and ‘lunacy’ were used to refer to people with mental health issues. At this time there was minimal consideration for the appropriate treatment needed to support these individuals. The asylum system was initiated as a safe space for people with mental health conditions, but quickly became a system of vastly oppressive institutions. Thus, creating institutions that housed people with significant mental health conditions as opposed to treating and curing them as it has originally proposed to do. This chapter will contextualise changes to legislation throughout the 18th and 19th centuries that were posed as progressive moves in mental health treatment. But that led to a continuation of the construction of ‘dangerousness’ in people with mental health illnesses. This will be demonstrated through the consideration of the long-standing effects that legislation, such as the Poor Law Amendment Act, held over the use of segregation for people with significant mental health conditions in the asylum system. This chapter will conclude by exploring the medicalization of the asylum system that led to the emergence of medical hospitals in the 20th century.