Drug and alcohol use presents a serious social problem for most countries in the world. Of particular concern is the well-documented relationship between substance use and crime, which has contributed to an increased popularity and willingness to utilize more forceful means to pressure substance users into treatment. Although compulsory/legally mandated treatment is appealing, it has been one of the most fiercely debated topics in the addiction field, raising a number of issues including ethical concerns and motivational considerations. In this context, the most important question to be answered is whether or not compulsory treatment is effective in the rehabilitation of addicted offenders. Regrettably, three decades of research into the effectiveness of compulsory treatment have yielded a mixed, inconsistent, and inconclusive pattern of results, calling into question the evidence-based claims made by numerous researchers that compulsory treatment is effective in the rehabilitation of substance users. The present paper provides an overview of the key issues concerning the use and efficacy of legal coercion in the rehabilitation of substance users, including a critique of the research base and recommendations for future research.