The appeal to allow the right to vote has been split into two parts, the first of which was heard earlier this month. The second part is back in the Supreme Court this morning.
Today's hearing focuses on whether or not the right to vote is entrenched in electoral law, meaning that to pass legislation to take away that right needs a vote of more than 75 per cent of the House of Representatives or more than 50 per cent at a referendum.
Lawyer for Arthur Taylor, Francis Cooke QC, said the Electoral Act encapsulated the right to vote.
Section 74 of the Act states that "every adult person is qualified to be registered as an elector", which Cooke said showed the right to vote "in a way that's consistent with the New Zealand Bill of Rights Act right".
That section of the Act is covered by section 268, which names it as a reserved provision and states it cannot be repealed or amended without the aforementioned percentages.
"Everyone becomes invested in that right when they become adults as defined," Cooke said.
"The Act does establish the right to vote and does protect the right to vote in the entrenchment provision."
If Parliament was to amend the right to vote to change the age of eligible voters, or to say only men could vote, or to say Maori or Chinese people could not vote, such a change could not be passed with an ordinary majority, Cooke said.
He is arguing the correct process wasn't followed when the law banning prisoners from voting was passed.
"How do we make sense of what Parliament has done in enacting and protecting the right of all 18-year-olds to vote, subject to this Act?
"What is entrenched doesn't have a bright line but that's the problem that Parliament created. There is no bright line here. We've just got to try and make sense of what Parliament has given us."
But Solicitor-General Una Jagose QC said section 74 of the Electoral Act was not entrenched in its entirety.
She said Cooke's response to many questions was that line drawing was difficult, but in her submission "268 does draw a bright line".
She said the Electoral Act delivered the way people could exercise their right to vote, but the right to vote itself existed independently from the Act.
Jagose pointed to the wording of each of the subsections of section 268, which all identified a particular section of the Act and went on to say "relating to" a piece of that section.
The subsection entrenching section 74 broke that pattern, saying "section 74, and the definition of the term adult in section 3(1), and section 60(f), so far as those provisions prescribe 18 years as the minimum age for persons qualified to be registered as electors or to vote".
Jagose said this meant the only thing being entrenched was the minimum age for voting.
Chief Justice Sian Elias said if some of the commas in the sentence had been distributed differently, it could clearly say that section 74 in its whole was entrenched, as well as the rest of the sections mentioned.
Jagose argued if that was the case, the rest of the sections mentioned would be put into their own separate subsection.
"It would be 'section 74 relating to the qualification of electors', and then we would have the age separately," she said.
Chief Justice Elias said the ambiguity of the Act was "very surprising".
"It's shockingly casual legislation for something as important as this," she said.
The hearing is expected to last the whole day.