There is an increasing involvement of lawyers and law firms in public affairs through activities that are aimed at influencing legislative and regulatory developments. Law firms offer services which can be regarded as lobbying, and yet, to the detriment of transparent policy-making, they are reluctant to register in the European Union Transparency Register (EUTR) and provide information about their activities. As growing attention is paid to the need to regulate lobbying at the EU and Member State levels, the question arises as to whether and to what extent such regulatory framework should also cover certain services provided by law firms, that is, legal lobbying. This Article charts the phenomenon of legal lobbying and its regulation in the EU context. It shows how the EUTR attempts to distinguish between legal services and lobbying by defining two lawyer roles: a legal expert, and an advocate. These roles allow the possibility to pinpoint two unresolved issues associated with legal lobbying: the scope of professional secrecy, and the meaning of the legal advice exception. An important conclusion is that regulatory clarification is necessary to resolve ambiguities and broadly address the implications that legal lobbying raises in terms of transparent and legitimate law-making processes.