The D-Notice system is a voluntary arrangement between the government and the media whereby the media agree not to publish or broadcast certain information in the interests of national security. It represents voluntary censorship on the part of the media. The alternative to the D-Notice system is legal action by the government to suppress allegedly sensitive material, for example, by use of the civil action of breach of confidence, or to punish the media after publication by use of the criminal law.;This book identifies a major deficiency in both the D-Notice system and the legal alternatives to the system. It maintains that the public interest, that is, the interests of the general public, is insufficiently represented in the operation of the former and is often not sufficiently recognized by the judiciary in the latter. The result, the author argues, is that material may be suppressed which has no connection with national security, but which instead exposes the government to embarrassment.;The book offers a comprehensive history and comparison of the D-Notice system in the UK and Australia. It analyzes issues pertaining to the relationship between free speech and the system and discusses the ""public interest"" in relation to the involvement of the government and the media. The author also explores the means by which the governments in both countries suppress information in the interests of national security.