In recent years there have been an increasing number of "incidents" involving diplomats, such as the storming of the US embassy in Tehran and taking of hostages, and the murder of a British policewoman by a member of the Lybian mission in London. Other less serious ones, like the flouting of traffic regulations and the non-prosecution of those stealing, have brought the question of immunity into the public domain. Why, it is asked, should law-abiding citizens put up with lawless behaviour from those who can retreat into the sanctuary of an embassy? The author explains why anyone engaged in diplomacy will insist that without immunity the task is impossible. He sets out the origins of the concept and discusses the legal and political rationale for the Vienna Convention on Diplomatic Relations, signed in 1961. He analyzes the tensions which have affected immunity since the early 1960s, and suggests practices which should be multilaterally adopted to help decrease the diplomatic and political risks inherent in the immunity system. Mr McClanahan served in the US Department of State and Foreign Service, 1945-1969.