Labor appointments are once again in the majority in the nation's highest court after Patrick Keane was appointed Australia's 50th High Court judge.

Attorney-General Nicola Roxon announced the appointment in Canberra on Tuesday morning.

New High Court Justice Patrick Keane. Credit:James Davies

Justice Keane, who is currently Chief Justice of the Federal Court, will replace Justice Dyson Heydon who will leave the bench in March when he turns 70, the compulsory retirement age for High Court judges.

The appointment will mean Labor appointments will be in the majority on the bench for the first time since 2005.