 McGrath was appointed to the Court of Appeal in July 2000 and to the Supreme Court in May 2005.In the 2007 New Year Honours, he was appointed a Distinguished Companion of the New Zealand Order of Merit, for services to the Appeal and Supreme Courts.In 2009, following the re-introduction of titular honours by the New Zealand government, McGrath accepted redesignation as a Knight Companion of the New Zealand Order of Merit.