There has been considerable debate for some time about the proper role of private enforcement in cartel enforcement. It arose again recently in the wake of the decision of the European Court of Justice in Pfleiderer. The Court had to decide whether to disclose to private claimants documents obtained by a national competition regulator through its immunity programme. It decided that disclosure was not prohibited by EU law but was a matter for a national court to weigh the interests of civil claimants against the need to protect immunity programmes. Similar issues have arisen in Australia. The paper provides a brief overview of immunity policy and the place of private enforcement and then examines the regulatory, legislative and judicial responses to the disclosure/immunity issue in Europe and Australia and considers whether the correct balance has been struck between the competing interests of private claimants and regulatory authorities.