Tetley's Super League VIII was the official name for the year 2003's Super League championship season, the 110th season of top-level professional rugby league held in Britain, and the eighth championship run by Super League.
The knock-on rule was modified so that if in the referee's judgement a player did not play at the ball, a knock-on would not be given.
Super League coaches voted 12-0 for new interchange and substitution rules for the 2003 season. The number of interchanges, which now included blood bins, increased from 6 to 12 using a pool of 4 substitutes. This change aimed to retain the element of wearing down a team's opponents during the game - which was considered part of the character of the sport.Stuart Cummings, the Rugby Football League's technical controller said the changes "bring us into line with the international rules" and ruled out future increases as well as declaring, "We will never see the unlimited interchange introduced into rugby league in Britain," a change that had caused controversy in Australia during its experiment there.