Former maverick MP and Supreme Court judge Robin Millhouse is being remembered for his contribution to law reform in South Australia after dying at the age of 87.

Key points: Millhouse was a member of State Parliament for more than 25 years

Millhouse was a member of State Parliament for more than 25 years Former SA Democrats leader Ian Gilfillan said he was "one of the most remarkable, unusual people you'd meet"

Former SA Democrats leader Ian Gilfillan said he was "one of the most remarkable, unusual people you'd meet" He was a campaigner for the legislation of prostitution

Mr Millhouse was a member of State Parliament for more than 25 years before going on to a career as a judge first at home and then overseas.

One of the most colourful characters in South Australian legal and political circles, Mr Millhouse was Australia's first Democrats MP.

He was also a devout Christian, a fitness fanatic, cycling enthusiast and ardent nudist.

Former SA Democrats leader Ian Gilfillan said Mr Millhouse was "one of the most remarkable and unusual people that you'd ever meet".

"A remarkable friend and a remarkable individual with a maverick personality," he said.

"He always kept true to what he believed to be the proper course of action, both practically and ideologically."

Mr Gilfillan said Mr Millhouse should also be remembered as a loving husband and father.

Among the reforms he helped bring about, Mr Millhouse was a driving force behind the introduction of seatbelts.

"It had the same opposition that applies to most reforms. A lot of people said they were unnecessary; they will hinder people," Mr Gilfillan said.

"It was the persistence and the dedicated targeting of Robin that achieved seatbelt legislation in South Australia."

Sorry, this video has expired Old footage of Robin Millhouse wishing 1960s and 70s premier Don Dunstan happy birthday

He said Mr Millhouse was essential in the evolution of the Australian Democrats.

"Had it not been for his influence with others that had been with him in the liberal movement, and the new liberal movement ... it's unlikely that the Australian Democrats would have evolved into what was virtually an Australia-wide and, quite a widely supported, political party," Mr Gilfillan said.

A champion for Maslins nudist beach

Former Democrats MLC Sandra Kanck described Mr Millhouse as a "man ahead of his time" who also had a mischievous streak.

"He was known for championing the nudist beach at Maslin Beach," she said.

"I can remember him showing me a photo of people on Maslin Beach and saying, 'Hasn't that guy got a nice bum?' and I said, 'Well, I suppose so' and he said, 'Well it's me'.

"There was something almost elfish about him."

Mr Millhouse entered Parliament in 1955 as the Liberal and Country member for the seat of Mitcham, which he held for the next 27 years.

After a brief stint as attorney-general in the late 1960s, he spent most of his Parliamentary time in opposition.

During the 1970s he became a thorn in the side of then premier Don Dunstan and was often described as the premier's only effective opposition.

A campaigner for the legalisation of prostitution, Mr Millhouse left politics in 1982 when he controversially accepted an appointment to the benches of the Supreme Court by the Tonkin Government.

When he turned 70, Mr Millhouse retired from the bench and was appointed Chief Justice of the High Court of the Pacific nations of Kiribati and Nauru.

Ms Kanck said he initiated inquiries "into things like drug law reform and he had bills for sex work reform".

"He was a person I was able to get along with really, really easily," she said.