Freedom of expression and national security are two of the most important necessities of human societies. Freedom of expression is one of the four essential conditions upon which the security of every nation and its citizens is founded. The others are freedom of worship, freedom from want and freedom from fear. Since independence in 1960, Nigeria has had 23 years of civilian and 29 years of military rule. Compared to military regimes, fundamental human rights, especially the right to free expression, are relatively more respected during democratic civilian dispensations. Military regimes in Nigeria have often, subtly and violently, restricted freedom of expression under the guise of protecting national security. The State Security (Detention of Persons) Decree is one of the legal instruments through which these regimes suppress freedom of expression. This book analyzes the application, by military regimes in Nigeria, of the decree in unduly restricting individual, group and media expressions and punishing their authors. This book is of great value to those interested in Nigerian history and politics, comparative civil/military rule and all lovers of free and open societies.