But the federal government's chief legal adviser, Solicitor-General Justin Gleeson, has enjoyed a relatively low profile outside legal circles – until now.

The 54-year-old silk and St Patrick's College Strathfield old boy is now the chief thorn in the side of Attorney-General George Brandis, and a very public brawl between the pair is showing no signs of abating.

What started as an important but pointy-headed legal debate about the independence of the Solicitor-General is now a feud about a far more tangible issue for voters: whether Brandis misled Parliament.

In an escalation of a toxic row that has simmered for months, Gleeson has flatly contradicted claims by Brandis that he was consulted about a move to stop ministers seeking the Solicitor-General's advice without the written approval of the Attorney-General.

Legal experts have warned the change could see the Solicitor-General, who sits at the apex of lawyers advising the government and appears in high-profile court battles, "frozen out" by the Attorney-General of the day.

Documents released at a Senate inquiry on Wednesday suggest Gleeson was not asked to advise on a marriage equality proposal, or on substantial revisions to a legally contentious plan to strip dual nationals involved in terrorism of Australian citizenship.

Brandis, who has rejected claims he misled Parliament, has picked a fight with a barrister renowned for his keen intellect and skill as an advocate.

The fourth of five children, Gleeson grew up in Sydney's inner west. His father Gerald was head of the NSW Premier's Department for more than a decade during the Wran and Unsworth Labor governments.

A former medallist at the University of Sydney and an Oxford alumnus, Gleeson started his legal career as a solicitor at the law firm now known as Freehills. He was called to the bar in 1989 and was appointed silk in 2000.

In 1986 he married Bernadette Brennan, daughter of former High Court chief justice Gerard Brennan, and the couple have two daughters.

Sydney silk Geoffrey Watson, who has known Gleeson since school days, says Gleeson has a "very committed, principled approach to social justice" and worked with "amazing" speed as a barrister.

"His brother Fabian, now on the NSW Court of Appeal, wanted to borrow a case report from Justin's room but did not want to go in because he knew Justin was preparing for a major cross examination in a big case," Watson recalls.

"Eventually Fabian had to go in, and when he did he found Justin behind his desk teaching himself Spanish."

The Gleeson brothers were foundation members of the prestigious Banco chambers in Sydney in 2005, with younger brother Justin the founding head.

Justin was appointed as Solicitor-General by the Gillard Labor government in February 2013, months before Fabian was elevated to the bench. He had acted in the role for four months.

In his swearing-in speech as a judge, Fabian joked that his younger brother had "warned me not to expect any lenient treatment in the High Court when my decisions are the subject of criticism".

It is a well-trodden path from Solicitor-General to the High Court, with Gleeson's predecessor Stephen Gageler now on the bench.

Brandis has been forced in recent months to hose down speculation he is seeking a spot on the High Court himself.

It is an unlikely prospect – but what happens next in the row between Brandis and Gleeson is likely to shape the careers of both men.