Justice Amanda Tonkin was sworn in to the Federal Circuit Court of Australia at a ceremony on Thursday, where she was praised for her integrity and forensic approach to the law.
Justice Tonkin was a teacher before she turned to law.
She worked for several years as a prosecutor with the ACT Director of Public Prosecutions, and was a Legal Aid commissioner in the ACT for 15 years.
In 1995, Justice Tonkin was called to the bar, where she spent more than two decades and earned a "reputation of diligence and fearless advocacy", Sarah Avery, president of the ACT Law Society said at the ceremony on Thursday.
"The Canberra legal community holds you in the highest regard for your intellect and integrity," Ms Avery said.
That high regard was evident in the crowd that came to watch her swearing-in ceremony at the Nigel Bowen Commonwealth Law Courts Building, spilling into a second courtroom.
Ken Archer, president of the ACT Bar Association, had seen for himself the determination and work ethic of Justice Tonkin.
He said the nickname Tonks - as she was warmly referred - said something about the court's new judge, "folksy, straightforward, and not too many pretensions".
ACT Senator Zed Sesejla, speaking at the ceremony, said Justice Tonkin's diligence and thoroughness, as well as her prodigious work ethic and commitment to justice had earned her praise among the legal community.
He described the new judge as a jazz and blues fan who made regular pilgrimages to the Byron Bay Blues Festival.
In her speech Justice Tonkin, one of very few women to have joined the bar in 1995, encouraged young barristers, especially women, to persevere with the profession.
Justice Tonkin becomes one of 65 judges on the Federal Circuit Court, which heard 93,000 cases last year.