Justice Lussick commenced his career in law in 1973 when he set up his own practice as a Barrister-at-Law in Sydney Australia. In 1973 he was admitted as a Barrister of the Supreme Court of New South Wales. In 1974 he was admitted as a Barrister of the High Court of Australia.
In 1986 he was admitted as a barrister and solicitor of the Supreme Court of Samoa. He was appointed Parliamentary Counsel and also served as Acting Attorney-General.
From 1986 to 1995 he served in the Samoan judiciary in various appointments to the District Court, Supreme Court, Court of Appeal, Land and Titles Court, and as Acting Chief Justice. He was also Chairman of the Public Service Board of Appeal.
In 1995 he was appointed Chief Justice of the Republic of Kiribati. As such, he was also President of the Court of Appeal. He served in this appointment until the year 2000.
In 1996 he was made a Fellow of the Commonwealth Judicial Education Institute.
From 1997 to 2000 he was Vice-President (Pacific Region) of the Commonwealth Magistrates’ and Judges Association.
From 2004 to 2012 he served as a judge of the Special Court for Sierra Leone and was Presiding Judge of Trail Chamber 2 which delivered the decision in the Charles Taylor case.
From 2012 to 2019 he was appointed by the United Nations as a judge of the United Nations Appeals Tribunal. He was President from 2014 to 2015 and First Vice-President from 2016 to 2017.
He was appointed by the United Nations as a judge of the Residual Special Court for Sierra Leone in December 2013.