Many of June Lowe's friends have a criminal record, just because they had homosexual sex before it was decriminalised in Western Australia in 1989.

So the long-time gay rights activist is excited that political momentum is building to clear their records of offences which no longer exist.

Last night, at a function to celebrate the Pride festival, WA Attorney-General Michael Mischin indicated he had the support of the Premier over his plan to expunge all historical homosexual convictions.

Mr Mischin said it was a symbolic and practical step towards equality.

"Work has been done on this to determine a 'best practice' model for achieving that end, and although I cannot commit Government by pre-empting any decision by Cabinet, the Premier has told me that he is supportive of that objective," he told the gathering.

His announcement brings the Government's position into line with the opposition, which pledged in August to quash the convictions under old anti-homosexual laws if elected in March next year.

The support of the two major parties makes it appear likely the required legislation will pass if it is introduced to Parliament after next year's election.

But it could still face potential hurdles in garnering the support of the Liberal Party room, particularly among conservative Christian MPs, and a new Parliament next year.

Regardless, Ms Lowe said the support of the Barnett government showed there had been a shift in attitudes towards discrimination against gays and lesbians.

"As a society we have moved forward enough that even the conservative parties feel comfortable with this," she said.

The move by Mr Mischin came after he was lobbied by the Law Society of WA in April.

In a submission, the society's president Elizabeth Needham pointed out that people with these convictions on their criminal record were still facing discrimination.

"In all likelihood, even after that conviction was spent, you would not ever be able to drive a bus, become a police officer, teach, voluntarily foster children or participate in any number of public services because you were once convicted, for all intents and purposes, for being homosexual," she wrote.

The New South Wales and Victorian parliaments have already passed legislation to expunge the offences from criminal records, while most of the other states and territories have signalled their intentions to follow suit.