New Zealand Sign Language has its roots in British Sign Language (BSL), and may be technically considered a dialect of British, Australian and New Zealand Sign Language (BANZSL). There are 62.5% similarities found in British Sign Language and NZSL, compared with 33% of NZSL signs found in American Sign Language.
Like other natural sign languages, it was devised by and for Deaf people, with no linguistic connection to a spoken or written language, and it is fully capable of expressing anything a fluent signer wants to say.
It uses the same two-handed manual alphabet as British Sign Language and Auslan, Australian Sign Language.
It uses more lip-patterns in conjunction with hand and facial movement to cue signs than BSL, reflecting New Zealand's history of oralist education of Deaf people. Its vocabulary includes Māori concepts such as marae and tangi, and signs for New Zealand placenames. (E.g Rotorua - mudpools, Wellington - windy breeze, Auckland - Sky Tower, Christchurch - 2 Cs, represents ChCh.)
In 1985, Marianne Ahlgren proved in her PhD thesis at Victoria University of Wellington that NZSL is a fully-fledged language, with a large vocabulary of signs and a consistent grammar of space.
The NZ Sign Language Tutors' Association (NZSLTA) was set up in 1992. Over the next few years adult education classes in NZSL began in several centres. In 1997 a Deaf Studies course was started at Victoria University of Wellington.
An important step toward the recognition of NZSL was the publication in 1998 of a comprehensive NZSL dictionary by Victoria University of Wellington and the Deaf Association of NZ. It contains some 4000 signs (which correspond to many more meanings than the same number of English words, because of the way signs can be modulated in space and time), sorted by handshape, not English meaning, and coded in the Hamburg Notational System, HamNoSys, as well as pictorially.
For some years, TVNZ broadcast a weekly news programme, "News Review", interpreted in NZSL. This was discontinued in 1993 after a joint survey of Deaf and hearing-impaired people found a majority favoured captioned programmes. Many Deaf people felt they had been misled by the survey. There has been no regular programming in NZSL since.
The bill received Royal Assent, a constitutional formality, on 10 April 2006. New Zealand Sign Language became an official language of New Zealand the day after Royal Assent.
The use of NZSL as a valid medium of instruction has not always been accepted by the Government, the Association of Teachers of the Deaf, or many parents. However, in light of much research into its validity as a language and much advocacy by deaf adults, parents of deaf children (both hearing and deaf) and educationalists, NZSL has since become — in tandem with English — part of the bilingual/bicultural approach used in public schools (including Kelston Deaf Education Centre and Van Asch Deaf Education Centre) since 1994. Victoria University of Wellington has courses in New Zealand Sign Language, although it has yet to develop a major program for it. AUT teaches a diploma course for NZSL interpreting.