The Justice Minister says it could be too difficult, but an Australian state has proved it's possible.

Victorian premier Daniel Andrews made a formal state apology in May to those convicted of being gay under historical laws and a scheme to expunge those convictions came into effect last September.

There are calls for the New Zealand Government to follow suit, but Justice Minister Amy Adams said it would need to be done on a case-by-case basis and that could prove too difficult.

Human rights lawyer, Anna Brown said it's important to examine each case individually.

“In Victoria, the laws also covered conduct which may be considered unlawful today. For instance, the crime of buggery included consensual sex but also non-consensual sex.”

The Victorian Commissioner for Gender and Sexuality said making a state apology to those convicted for being gay was a lot of work, but the right thing to do.

The scheme to expunge historical convictions for homosexuality came into effect last September.

Rowena Allen said the expungement scheme allows every individual person to have their case reviewed.

“We do know that thousands, literally thousands of people, were convicted under this very unjust law. [Daniel Andrews] was right and timely to make that full apology.”

This Saturday marks 30 years since homosexual law reform in New Zealand.