He selects the roasted snapper, I opt for the lamb rack, and we share a side salad. For drinks, it's mineral water and we both order coffees as we outlast our fellow diners. The Land and Environment Court was the first so-named court in the world when it was established in 1979, according to Ben Boer, Emeritus Professor at Sydney Law School and Preston's first lecturer on environmental law, and a long-time friend and collaborator. There are now about 700 such courts globally. But long before he got the top job at the court, he helped found another key organ of environmental law: the Environmental Defender's Office of NSW. It was the EDO that last week won a ruling in the Federal Court that found Environment Minister Greg Hunt had not properly considered advice on two threatened species, the Yakka skink and the ornamental snake, when approving Adani's huge $16 billion Carmichael coal mine in Queensland. The verdict prompted Prime Minister Tony Abbott to declare that courts were being used to "sabotage" mining projects, adding that Australia "must, in principle, favour projects like this". The NSW Bar rejected the comments..

While our lunch preceded Abbott's outburst, Preston defended the importance of judicial independence, and later remarked that miners too often view environment checks as merely red tape. Preston makes time for our lunch between his court duties, ongoing research for a book on environmentally sustainable development, and his work for a global effort to find ways the law can be used to curb climate change. He also teaches biodiversity law at Sydney University, and has helped develop environmental law in China and Thailand – two nations particularly in need of regulatory control – and remains a keen bushwalker when he gets the time. From Kokoda to Kakadu Preston has always had a keen interest in nature and the environment. He tells me how as a boy he grew up propagating and selling his own tropical (and mostly native) plants. Later when he was at university in 1981, Preston along with some fellow students, hiked the Kokoda Track in Papua New Guinea "before it was popular". With no public maps available, he headed to the Mitchell Library cartographers for guidance.

"I went along to find these maps and the only ones were from the war," he said. "There were the ones that showed the leper colonies, and things like that." There were also profile maps, showing single line drawings of the shape of various hills and mountains one might spy along the way. "So I thought, How hard can it be? You start at one end of the country and you're going to end up on the other. You can't go too far wrong can you?" he said. Using a stratagem of taking "the road more travelled" sometimes resulted in a dead end at some villager's sweet potato field. The students, though, still managed the track in five days, "with a day off". Heading out from Lae, the travellers were advised to visit an offshore island known for its volcano and a hospitable local chief who wore a display of the finest bird of paradise feathers. It was Manus Island, better known now for hosting the controversial Australian offshore processing centre for asylum seekers.

"We were given pride of place, which is a room over the pigs," Preston recounts of the space above what was – literally – the chief's piggy bank, given the animals' value as currency. "Well, we are the lucky ones," he remembered thinking – a response likely to be more poignant if he revisited the place today. Manus Island became host to would-be asylum seekers in 2001, with the site closing in 2008 and reopening in 2012. Back at university, Preston graduated with a first-class honours degree in law in 1981 and also a bachelor's degree in accounting after deciding a triple degree with geography might be "a bit too crazy". One of his first jobs after graduation was to serve as a law clerk to Justice Kevin O'Leary of the Northern Territory Supreme Court. Justice Preston had been kayaking in the Kakadu with his girlfriend – and now wife – Judith and turned up for the impromptu interview wearing just shorts, a T-shirt and runners. Preston got the job despite replying to the judge's request for a curriculum vitae by saying: "The crocodiles in Kakadu didn't want to read it, so I didn't bring one."

After 18 months in Darwin, where Judith worked on early Aboriginal land claims with the Northern Land Council, the couple were lured back to Sydney. EDO launched Boer was anxious to set up what would become the EDO NSW to advocate on behalf of communities affected by major projects, to capitalise on a promised gift of $10,000 from property firm Lend Lease and $1000 from Esso.** Preston became the EDO's first principal solicitor, finding pushback from legal firms disliking competition and surprisingly little support from big environmental NGOs such as the Australian Conservation Foundation. "They were more into direct action and lobbying and that sort of thing," Preston said. "They could not really see using the courts as a tool."

At the time, court costs weren't granted to winners and so the EDO almost closed. Legal aid, though, came to the rescue after Preston convinced the government they met a poverty test. "Poverty is not just about your lack of dollars," he said. "If you have a degraded environment, you're impoverished as well." Among the early wins was a case involving an action against a development near the Jenolan Caves, west of the Blue Mountains area. Investigations found the relevant minister had acted outside her powers, forcing her to change the law – but not before attacking Preston, who was then the solicitor running the case. "Well, did that cause a kerfuffle! She stood up in Parliament – coward's castle – and badmouthed me, this 'supposed solicitor' said this and this, 'and so I introduce the bill to retrospectively approve all my decisions'," he said. That response, Preston says, is not unlike the reaction he's received from mining companies and politicians after some of his verdicts in the Land and Environment Court. Most prominent of these was the April 2013 decision – upheld on appeal – to overturn the state's approval given to Rio Tinto for its Warkworth open-cut coal mine near the Hunter Valley hamlet of Bulga.

After leaving the EDO to join the bar in 1987, Preston developed a practice involving environmental and planning law among other areas. He was appointed chief judge of the court in November 2005. 'Environmentally literate' Preston said criticism from environmental groups over the small size of some penalties handed out during his tenure is probably unfair. One issue is that the plaintiff, often a government agency such as the Office of Environment and Heritage, sometimes pursues only minor breaches or the secondary party involved, such as a subcontractor instead of a mine owner. One example is the June 2015 judgment against Minova Australia, a contractor now owned by Orica. The company was brought in by mining giant Xstrata (owned by Glencore) to pour cement grouting into fissures opened up by the West Wallsend underground coal mine in the Sugarloaf State Conservation Area.

"[Xstrata] always knew it was going to have massive effects, but it's had even greater massive effects, whole rocks, landscape, dropping down," Preston said. The grouting was a disaster, with some of the hundreds or thousands of tonnes of cement poured into the cracks oozing into a creek below "like toothpaste". In the end, Minova forked out half a million dollars for the clean-up, including bringing in helicopters to carry out waste, more than the fines and court costs of about $300,000. "You have a mining company creating massive problems, then you've got the people directing the remediation of the problem which itself is creating problems, telling them they have to do it in a particular way, and they won't know whether it is going to work. But those persons are not prosecuted," Preston said. He says that having a specialist court with judges well read in environmental issues does not imply – as some miners argue – that developers won't get a fair hearing.

"You should be environmentally literate," he said. "All courts strive to make the right decision and you're more likely to make that if you've got more knowledge." "What [critics] are really saying is they want a partisan person ... They don't want an independent, impartial arbitrator." Life and times: Born: 10 June 1958 Married: 24 August 1984; three children, Matthew, Rebecca, Rachael

Education: Knox Grammar School 1979 Bachelor of Arts (Accountancy major), 1981 Bachelor of Law (First-class Honours), 1985 Co-founder, principal solicitor of EDO NSW 1987-2005 Barrister of the NSW Supreme Court, High Court 2005 Appointed chief judge of the Land and Environment Court

**An earlier version of this article incorrectly gave the funding as including James Hardie.