When his father was named Governor of New Jersey in 1738, his son's name appeared on his list of councilors. Less than a year later, Governor Morris named Robert the Chief Justice of the provincial Supreme Court. His commission was set to run "during good behavior of same", which differed from that of his predecessor, Robert Lettis Hooper, whose term was determined to run "through the royal pleasure". His term was marked by increased punctuality and efficiency. During his term in 1744 he was elected a member of The American Philosophical Society. Following a long trip to England in 1749, he was made Deputy Governor of Pennsylvania in 1754 and elected a Fellow of the Royal Society in 1755 after his return. He served as Deputy Governor from 1754 to 1756, during the French and Indian War. and the Pennsylvania Assembly became a duel between Morris and Benjamin Franklin. The main point of contention was the adamant refusal of the Penns to countenance any tax upon their lands in Pennsylvania, even for provincial defense. During the summer and autumn of 1755, while the frontier burned and the settlers fled for their lives from attacks by French-friendly Indians, the proprietors and the Assembly locked in legislative stalemate. Morris defended the proprietors and Franklin spoke for the people of Pennsylvania. In late July, 1755, the Assembly authorized the expenditure of 50,000 pounds for provincial defense following the defeat of Major General Edward Braddock by the French and Indian soldiers near Fort Duquesne in western Pennsylvania. To raise the money, the Assembly approved a property tax, applicable to all real and personal property within the province. Morris vetoed the tax bill with suggestions for amendment that would exempt the proprietary estates. Franklin drafted the Assembly's response, the gist of which was that taxing the proprietary estates, along with all the other estates in the province, was "perfectly equitable and just." Eventually, Morris admitted that the terms of his commission prohibited his accepting any measure that taxed the proprietary estates. This prompted Franklin to bypass Morris and take on the proprietors themselves, which led to Franklin's removal to London in 1757 to argue the Assembly's side in the dispute with the proprietors. In 1756, Morris resigned his commission as Chief Justice and made another long trip to England. Wiliam Aynsley was made Chief Justice in his absence. When Morris returned in 1760, he claimed he was still Chief Justice on the grounds that his resignation had never been formally accepted. As Aynsley had died and Morris was the best person available to fill the post, he was reinstated and served in that capacity until his own death in 1764.
Personal life
Morris was married to Elizabeth Stogdell. Together, they were the parents of:
