This paper addresses the conflict between the ethical and legal responsibilities of researchers engaged in illicit drug use research. Fundamentally, the primary ethical responsibility is to protect research subjects from any harm which may come to them as a consequences of having taken part in the research. Legal responsibilities, however, might lie in assisting police with their enquiries into the conduct of an individual who is a research subject, and allowing research data to be searched and possibly used in evidence against the individual. There is no Western Australian legislation which protects research, nor Australian legislation which can be applied to most studies. Using two case studies, we give examples of the conflict and suggest that legislation may be the most effective way to overcome it. However, we also raise a number of issues which would need to be considered before solutions are enacted.