A poker player and author on the subject, Jacoby was convicted of a gambling charge in 1944 while in the navy but acquitted of a charge of conduct unbecoming an officer and a gentleman. Although he did not pursue a career in competitive chess and did not write on the game, he was nevertheless a strong player. When in college, Jacoby beat US chess champion Frank Marshall, and in 1963, in a rapid-transit game, he played a draw with Tigran Petrosian, the then world champion.