This chapter explores key legal issues that may be encountered when conducting Internet-based research  and suggests considerations and strategies that researchers may draw on to prevent legal risk. It examines the distinction between legal and ethical requirements, notes the international and cross-jurisdictional nature of online research, particularly the fundamental differences between  US and European regulatory frameworks, and considers the implications this may have for data transfers and other research business. The distinction between data protection and privacy is considered, using the UK legal position as an example and also briefly profiling the position in other EU member states and in the US. The chapter then addresses considerations relating to Intellectual Property, ownership and authorship. Copyright law in specific application to online research is profiled, as is the burden of legal liability on online researchers. Main legal considerations are illustrated by case study examples, either hypothetical or based on real cases. The chapter recommends that researchers think in terms of the legal considerations raised over the life cycle of personal data in online research. The best response to legal risk is the embedding of legal compliance processes into the overall research project, rather than regarding such considerations as a matter solely for the initial stages. Best practice involves risk assessments, effective administration and documentation, security arrangements, and considered data retention practices.