He said section 269 of the Electoral Act 1993 entrenched prisoner voting rights, which was why a supermajority was required to amend it.
But all three courts have agreed the entrenchment only extended to the minimum voting age.
Prior to the 2010 Amendment, prisoners serving life sentences, preventive detention or jail terms of three years or more were already disqualified from voting. The amendment extended this disqualification to all serving prisoners.
Part of the Electoral Act creates a number of reserved provisions designed to entrench certain aspects of the electoral system.
The Supreme Court had to determine whether the wording of the act meant all of the eligibility criteria listed in the act were to be treated as reserved provisions, requiring a supermajority before amendment.
The appellants argued the right to vote and the minimum age were intrinsically linked.
The case for the Attorney-General was that the language of the relevant section of legislation was clear and that all that was entrenched was the minimum voting age.
It was also submitted that there was no basis for the court to make the distinction between fundamental aspects of the right to vote and the mechanical provisions.
The Supreme Court dismissed the appeal, with the majority finding entrenchment only extended to the minimum age requirements, and that the text of the statute could not be read in any other way.
"Plainly, s268 is intended to make it more difficult to amend or repeal the reserved provisions and so give the matters reserved greater protection from amendment or repeal than other aspects of the electoral system," the judgement said.
"However, when the matter is considered in context, it is clear that it was not the parliamentary intention to entrench anything other than the minimum voting age."
Chief Justice Sian Elias disagreed, saying the natural reading of the section was that it entrenched all qualifications for electors.
She said the Bill of Rights Act enforced this.