Justin Gleeson has resigned his post as the government's chief legal adviser. Credit:Andrew Meares The men had been at loggerheads over a legally binding direction issued by Senator Brandis before the July 2 election which prevented ministers, including the Prime Minister, seeking advice from Mr Gleeson without his written approval. Legal experts had expressed concern the directive may mean the Solicitor-General, who holds a statutory office and gives independent advice on matters of national significance, is "frozen out" of advising the government of the day. A Senate committee is due to report by November 8 on whether Senator Brandis misled Parliament by claiming he consulted the Solicitor-General on about the move, a claim Mr Gleeson flatly denied. Senator Brandis has conceded he did not raise the prospect of a binding legal direction with Mr Gleeson at a meeting on November 30 last year because he had not yet decided on that course of action.

Illustration: Cathy Wilcox However, he told the Senate inquiry his legal obligation to consult did not require it be done "in some specific fashion" and there was consultation on the general "subject matter". He has insisted the direction was merely "administrative housekeeping" and consistent with the law and historical practice. Illustration: Ron Tandberg. But Mr Gleeson told the Senate inquiry the directive was unlawful and effected a "radical" change to the role of solicitor-general.

Former solicitor-general Gavan Griffith, QC, who served during the Hawke, Keating and Howard governments, said in an explosive submission to the Senate inquiry that it was akin to keeping a "dog on a lead" and risked politicising an independent office. Fairfax Media has previously revealed Senator Brandis sought advice from the private bar on issues ranging from the same-sex marriage plebiscite to the proroguing of Parliament before the election. It triggered accusations he was "shopping around" for opinions he regarded as more politically convenient, but Senator Brandis said his Labor counterpart Mark Dreyfus had also sought second opinions in office. Mr Dreyfus said on Monday that Mr Gleeson's resignation "is a direct result of the Attorney-General's disgraceful treatment of Mr Gleeson and his office". "It is not Mr Gleeson who should have resigned today – it is Senator Brandis," Mr Dreyfus said.

"The Commonwealth has lost from its service a great legal mind and one of the most experienced constitutional lawyers in this country as its most senior legal adviser." Stuart Clark, the president of the Law Council of Australia, said Mr Gleeson's decision was "both selfless and honourable". He said it was "critical that the legal advice which the Solicitor-General provides to government ministers and their agencies is frank, fearless and independent." In the letter to Senator Brandis, Mr Gleeson said he had come to the conclusion to resign "with regret, but the best interests of the Commonwealth can be served only when its first and second law officers enjoy each other's complete trust and confidence within a mutually respectful relationship". "When such a relationship is irretrievably broken, as is the case here ... there must be some resolution to the impasse," he said.

Senator Brandis said in a statement: "In the circumstances, Mr Gleeson's resignation is the proper course of action for him to have taken." He said he would "immediately take steps to identify and recommend to the Cabinet a suitable person to be the next Solicitor-General". "In the meantime, the government will recommend to His Excellency the Governor-General the appointment of Mr Tom Howe PSM QC as the Acting Solicitor-General." Mr Howe is chief counsel for dispute resolution at the Australian Government Solicitor. The resignation will take effect on November 7. Mr Gleeson said in his letter to Senator Brandis that he considered the notice period "should be the minimum necessary in the circumstances".

The resignation came as no surprise to the legal profession. It is understood Mr Gleeson has sounded out opportunities to go to the London bar to specialise in international arbitration. Sydney silk Andrew Bell, SC, has been touted as a potential successor to Mr Gleeson. But senior lawyers have raised concerns in private about whether the role is now too politicised to attract high-calibre candidates. Former High Court chief justice Sir Anthony Mason, a former Commonwealth Solicitor-General, said at an event in Sydney on Monday evening that Senator Brandis' interpretation of the law was a "big stretch". Senator Brandis had said the Commonwealth Law Officers Act required all requests for legal advice to be made through the office of the Attorney-General. But Sir Anthony said the Attorney-General could not say "yes or no" to a request for advice and he had routinely advised government departments without a referral.

However, he also said the Attorney-General could "seek advice from other counsel" and, "unlike the Pope, the Solicitor-General has no claim to infallibility".