Forbes was born in Bermuda in 1784. His grandfather, Dr. George Forbes had moved to the Bermudas after the Battle of Culloden. He went to London at the age of 19 to study law. He passed the exams and became a lawyer in 1812. He returned to Bermuda but went to back to England 3 years later. In 1816 he was made the first Chief Justice of Newfoundland. He lived in Canada until 1822. The government asked for his advice about setting up a proper legal system in Australia. He was asked to be the first Chief Justice of New South Wales in June 1823. Forbes was officially given the job in October 1823.