Events in recent years have heightened public awareness of matters of national and international security. The role of Australia's security and intelligence agencies - and the control and protection of the critical intelligence information that they generate, share and analyse - is also increasingly a matter of public concern. Criminal prosecutions hightlight these issues most starkly, but problems of principle and practice can arise in a wider array of matters. Classified and security sensitive information is used in administrative decision-making by government officials in circumstances that may give rise to subsequent legal proceeings. Although less common, classified and security sensitive information also may be relevant in a civil lawsuit, particularly where the Government is the defendant. The Terms of Reference for this inquiry asked the ALRC to assess the effectiveness of the various existing mechanisms designed to prevent the unnecessary disclosure of classified and security sensitive information in the course of official investigations and criminal or other legal proceedinsgs. The ALRC was also asked to report on whether there were any other approaches, including non-regulatory alternatives, which would improve performance in this area.