As time went on more branches of government became involved with book censorship including the police, Post Office, courts, Executive Council, Cabinet, and the Department of Justice.
Before the Act, many books were banned solely on the basis that because consensual sex between men was a criminal offence in New Zealand, any publication that dealt with homosexuality was dealing with crime and was therefore indecent.
[6] This article contains lists of books, comics, librettos, and pamphlets that have had legal restrictions on importation, sale, possession, or exhibition in New Zealand.
The earliest New Zealand legislation solely for the purpose of censorship was the Offensive Publications Act 1892,[7] although Customs regulations prohibiting the importation of indecent material had existed since 1858.
In May 1921, following the First Red Scare, a cabinet directive came into force prohibiting "any document which incites, encourages, advises, or advocates violence, lawlessness, or disorder, or expresses any seditious intention".
This changed in 1939 when the High Court[a] considered factors such as literary merit and circumstances of publication in its ruling on The Decameron by Giovanni Boccaccio.
[17] During World War I, power was given to the New Zealand Defence Force and later to the Customs Department to prohibit the importation of literature that was considered undesirable, usually for being seditious.
[68] Censorship of books, pamphlets, newspapers, telegraph, radio, mail, and public speech was extensive during World War II.
[91] Books were withheld for various reasons, including interfering with the war effort, having ties to communism, and being likely to cause strong sectarian strife or bitterness.
Minister of Customs Walter Nash, having been a bookseller's agent, had a special interest in books and took charge of this branch of censorship.