 At an IIHF congress in 1969 , officials voted to allow body @-@ checking in all three zones in a rink similar to the NHL . Prior to that , body @-@ checking was only allowed in the defending zone in international hockey . The IIHF later described the rule change as " arguably the most substantial and dramatic rule changes in the history of international hockey " because it allowed for a more aggressive game . The rule , which was first applied at the 1970 World Championships , was controversial : IIHF president Bunny Ahearne feared it would make ice hockey " a sport for goons . " Several other rule changes were implemented in the early 1970s : players were required to wear helmets starting in 1970 and goaltender masks became mandatory in 1972 . In 1992 , the IIHF switched to using a playoff system to determine medalists and decided that tie games in the medal round would be decided in a shootout . The IIHF decided to test a new rule in 1997 that would allow two @-@ line passes . Prior to that , the neutral zone trap had slowed the game down and reduced scoring . At the 1997 World Championships , teams were allowed to decide if they wanted to test the rule . Although no team accepted the offer , the rule was adopted . The IIHF described it as " the most revolutionary rule change since allowing body @-@ checking in all three zones in 1969 . [ ... ] The new rule almost immediately changed the game for the better . The 1999 IIHF World Championship in Norway was a stark contrast to the finals the year before with many more goals scored and with end @-@ to @-@ end action – not defence – dominating play . " 
