He attended St. Joseph's College, Hunters Hill where he captained the senior debating team and matriculated in 1935 winning a scholarship to study arts and law at Sydney University.
[5] He was recalled to support the militia in the defence of Australia and was involved in the Owen Stanley campaign and fought on the Kokoda Track as a staff captain with 7th Division HQ.
Prentice was responsible for many leading judgments, particularly in the area of constitutional interpretation, which have had a profound effect on the development of the law in Papua New Guinea.
[6] In 1978 Prentice presided over a traffic accident case in which Morrie Modeda - accused of a dangerous driving charge, occasion a man's death - was hacked to death by relatives of the deceased as he and court party including Prentice attended an inspection at the site of the accident.
In the concluding proceedings Prentice termed the action "cold-blooded, planned treachery" and described it as a "lawless and disgraceful episode".
[8] A devout Catholic, William Prentice was a member of the Thomas More Society for 55 years and served as councillor and honorary secretary in 1952-54.