Elias is due to stand down in March next year, having reached the compulsory retirement age of 70 for judges.
The government is only at the early stages of choosing a replacement. Attorney-General David Parker has been briefed on the process, which sees the Prime Minister making the final decision.
Elias delivered the speech as the Maxim Institute's Sir John Graham lecture, the first to have been given since his death in August last year.
In speaking on New Zealand constitutional underpinning, Elias describes centuries of legislation and declarations, and the role of common law created through court judgments.
In speaking on common law, Elias recalled telling a senior government minister of a paper she was preparing for a legal conference on judges' contribution to the law.
"That's easy," she quoted the unnamed female minister. "Judges apply the law."
True, Elias told the gathering in Auckland's Heritage Hotel, but "the difficult question is how judges identify what is the law they must apply".
Elias said the law was more than just "enacted rules" - statute passed by government - which was a "common misconception".
"The decisions of the courts are themselves law."
Elias said she was not seeking to provoke and was "content to accept that the courts are junior players in the development of law".
But she said common law was an agent of change, with legal precedent bringing modernity to statute.
Speeches by Elias have caused controversy between her and previous governments.
Her "Blameless Babes" speech in 2009 criticised punitive sentencing policies and brought a sharp rebuke from then-Justice Minister Simon Power.
Elias rose to the Supreme Court when it was formed in 2004, having been appointed Chief Justice in 1999.
Elias' legal career enjoyed a solid foundation and rapid ascent.
She was admitted to the Bar in 1970 after studying law at the University of Auckland.
Further study in the United States led to practise as a lawyer in Auckland in 1972.
She served as a law commissioner from 1986 to 1990, was appointed Queen's Counsel in 1988 and a judge of the High Court in 1995.
Elias is married to Hugh Fletcher, former CEO of Fletcher Challenge and former University of Auckland chancellor.
Sir John Graham was long-time headmaster of Auckland Grammar, a former All Black and University of Auckland chancellor.