In 1893, Griffith retired from politics to head the Supreme Court of Queensland. He was frequently asked to assist in drafting legislation, and the Queensland criminal code – the first in Australia – was mostly his creation. Griffith was an ardent federationist, and with Andrew Inglis Clark wrote the draft constitution that was presented to the 1891 constitutional convention. Many of his contributions were preserved in the final constitution enacted in 1900. Griffith was involved in the drafting of the federal Judiciary Act 1903, which established the High Court of Australia, and was subsequently nominated by Alfred Deakin to become the inaugural Chief Justice. He presided over a number of constitutional cases, though some of his interpretations were rejected by later courts. He was also called on to advise governors-general during political instability. Griffith University and the Canberra suburb of Griffith are named in his honour.
