​A Substance Misuse Psychology Expert is a psychologist who specialises in the assessment, diagnosis, and treatment of mental health conditions related to substance misuse and addiction. They focus on understanding the psychological and behavioural aspects of addiction, including the impact of substance misuse on an individual’s cognitive functioning, emotional well-being, and behaviour. In legal settings, they act as expert witnesses by providing expert witness reports that assess the psychological effects of substance misuse on an individual’s actions and mental state. These reports are crucial in cases involving criminal behaviour linked to addiction, personal injury claims, or assessments of mental capacity and fitness to plead. Their insights help the court understand how substance misuse influences decision-making, behaviour, and mental health, assisting in making informed legal decisions.