Brown has taken to the airwaves to reject criticisms of Melbourne barrister Brian Walters, who is running for the Greens in the seat of Melbourne.

Walters, the president of Liberty Victoria, proudly boasts on the Greens website that he has worked on issues involving asylum seekers, terror laws and police powers.

However, media reports over the weekend also revealed that Walters is currently acting for Downer EDI, which has a significant interest in RTL, a joint venture that operates the Yallourn open cut brown coalmine in the Latrobe valley.

WorkSafe Victoria has initiated legal proceedings against RTL after a union delegate was killed at the mine while conducting maintenance work in 2006.

This has prompted the sitting member for Melbourne, education minister Bronwyn Pike, to call into question the environmental and ethical principles of Walters.

"Bronwyn Pike has called me a hypocrite, but I believe that in a democracy, it is hypocritical to say one thing and do another," Walters told Lawyers Weekly. "At the last state election, the Victorian government had a central promise that it wouldn't introduce a desalination plant, but we now have this massive billion dollar white elephant.

"Now that is hypocrisy."

In June 2007, the Bracks Labor government announced it would build one of the world' largest desalination plants at Wonthaggi, on the South Gippsland Bass Coast.

At the previous Victorian election in November 2006, then Premier Steve Bracks discounted the construction of a desalination plant as being too expensive and an intrusion on the community.

Bob Brown has also appeared on ABC television and radio to accuse the Labor party of engaging in "dirty politics".

"You [barristers] take the case brought to you, otherwise you would have people who were defenceless in situations like this," Brown said. "No wonder he's [Walters] in demand because he's respected because of his great record in the courts in Victoria defending all and sundry who needed his help.

"It's a very ethical thing."

Walters has also defended his representation of Downer EDI and his running as a Greens candidate, telling Lawyers Weekly that he takes the 'cab rank' principle seriously.

The expression 'cab rank rule' refers to the obligation of a barrister to accept any work in a field where he or she has a competency.

"An important aspect of the rule of law as that as a barrister, you accept a brief if it is offered to you," Walters said. "I have knowledge of OHS regulations in Victoria, I was offered the brief [by Downer EDI] and it was my duty to accept it."

Labor has held the state seat of Melbourne for many years, but after former Slater & Gordon partner Adam Bandt took the federal seat of Melbourne for the Greens, it has been targeted as one of four inner-city seats the Greens hope to win. This has prompted the Victorian Premier, John Brumby, to call on Liberal Party voters to preference the Labor Party ahead of the Greens in those seats.

The Victorian election will be held on 27 November.