He has a longstanding reputation of advocacy in the areas of law, social justice, refugee protection, reconciliation and human rights activism.
[citation needed] He is a fourth generation Australian and is of Irish descent on both sides of his family and also has German ancestry from his paternal grandmother.
[6] On 15 August 2017, Brennan stated that if the law was changed to require clergy to report child sexual abuse learned of during confession that he would consider breaking it.
[7] During the 2017 Australian Marriage Law Postal Survey, Brennan dissented from traditional Catholic teaching, telling the media he would vote in favour.
[8] Following the survey, Brennan was appointed by then prime minister Malcolm Turnbull to serve on a Philip Ruddock-led review into religious freedoms.
He equated the trial to a left-wing version of the broken criminal justice system in Queensland during the 1970s, saying that even Aboriginal people had not been treated as prejudicially by the worst of 19th-century judges.
[11][12] In 1995, Brennan was appointed an Officer of the Order of Australia (AO) in recognition of service to Aboriginal Australians, particularly as an advocate in the areas of law, social justice and reconciliation.