A group campaigning to lower the voting age to 16 will head to the courts again today to try convince the Court of Appeal the current age is unjustified discrimination.
Make It 16 campaign's argument failed in the High Court in Wellington last year.
It argued the voting age being set at 18 was a breach of section 19 of the New Zealand Bill of Rights Act 1990.
Make It 16 co-director Cate Tipler said the group would argue while the High Court agreed the voting age was discriminatory, it was wrong to conclude discrimination was justified.
"The Crown was not able to provide any good reason as to why the rights of 16 and 17 year olds should be limited in this case, because there is none."
Make It 16 legal and policy leader Thomas Pope-Kerr said the group was confident its argument would be successful.
"The voting age of 18 is unjustified age discrimination. We say that because section 19 of the Bill of Rights Act protects against age discrimination if you're over the age of 16.
"Therefore there is discrimination and we say that it can't be justified... There is simply no excuse not to expand the vote to 16 and 17-year-olds."
While the court could not change the voting age, if it agreed with the group's argument it would go a long way to achieving a law change through parliament, he said.
"It does have a very important moral weight. So this is just one part of the campaign."
There was international momentum towards lowering the voting age, he said.
"There are plenty of other countries that do have a voting age of 16. The two most prominent examples of that for us are Austria and Scotland who have had the age there for quite a few years.
"And we see Wales the other day changed it as well so it's definitely a building movement around the world."
The voting age for local body elections can be achieved by a 50 percent government majority under the Local Electoral Act 2001, while a change for the general election required a 75 percent majority or a referendum.
Pope-Kerr said Make It 16 was not in favour of a referendum.
The hearing is set down for one day.