A youth-led campaign to lower the voting age to 16 is being heard in the Supreme Court today.

Make it 16 will have its case heard at the Supreme Court after failing in the group's efforts in the High Court and Court of Appeal in 2020 and last year.

They argue their case is a human rights issue.

"A formal declaration from the Supreme Court would be a powerful message to Parliament that they should fix this breach of our rights," Make It 16 co-director Cate Tipler said earlier.

"It would force Parliament and the Government to see this as a priority and boost the movement for change."

Tipler said receiving leave to appeal to the Supreme Court in the push to get the voting age lowered from 18 in time for this year's local body elections was "very exciting".

"This means rangatahi will get their day in the Supreme Court. Preventing me and other 16 and 17 year-olds from voting is unjustified age discrimination. It is a breach of the Bill of Rights."

The group, formed in July 2019 by youth activists both above and below voting age, are advocating for "more people's voices to count in our democracy", according to their website.

Make It 16 co-director Sanat Singh said the Supreme Court granting leave for a further appeal presented an opportunity to get a formal declaration from the highest court that preventing 16 and 17-year olds from voting is unjustified age discrimination.

Attorney General David Parker's position is that the earlier High Court decision was correct for declining the declaration Make it 16 seeks.

He said section 12 of the NZ Bill of Rights Act, which provides that every New Zealand citizen over the age of 18 can vote in parliamentary elections, settles any limitation in respect of the voting age.

Local Government elections will be held on October 8.