He advocated for gay and lesbian rights, including for those serving in the NSW police force.

The young Marsden, born the first of seven children in Lismore, grew up a Catholic in Campbelltown, where his parents owned a pub. He was educated at St Joseph’s College, Hunters Hill and De La Salle College in Armidale, and attended a seminary, though he left before taking vows.

As the Milat family lawyer, Marsden defended infamous serial killer Ivan Milat in 1974, getting him off two rape charges, but was sacked by the defendant before his most high profile trial. He later expressed regret that his successful defence of Milat paved the way for the death of seven tourists. Marsden had also planned to be on the defence team for former Iraqi president Saddam Hussein, citing a strong conviction that every person should be entitled to a lawyer.

The controversial barrister also sued the Seven Network in Australia’s longest-running defamation suit, which was in and out of courts from 1995 to 2003. Twice, programs on the network had alleged that Marsden had paid for underage sex. Marsden’s decision to allow his private life to be ransacked by prosecution and defence was vindicated when in 2003, Seven was ordered to pay a multimillion dollar settlement.

Marsden was holidaying with friends in Turkey when he died, at around 5am Sydney time on Thursday 18 May. His death followed a three-year fight against stomach cancer. “John chose not to take advice about travelling in his poor condition but he has been defiant for all of his life and he died the same way — defiantly. He fought it to the very end,” said his brother Jim Marsden. “John is survived by his two brothers and three sisters. We are all devastated as I am sure are his many friends in the Australian community, particularly the gay community, and the community of his beloved Campbelltown.”

President of the NSW Law Society, June McPhie, said Marsden was a great civil libertarian and had been extensively involved with many organisations in the Macarthur region for more than 35 years. “His passion and principles transcended political barriers,” she said. “He was larger than life, he lived life to the fullest and he had the courage of his convictions. [A] trusted colleague, [he was] generous to the fault and a true gentleman. He believed that if you ran a business in the local community then you should put something back into that community. He will be sadly missed,” she said.