<P> Zone defenses are common in international , college , and youth competition . In the National Basketball Association , zone defenses were prohibited until the 2001 -- 2002 season , and most teams do not use them as a primary defensive strategy . The NBA has a defensive three - second violation rule , which makes it more difficult for teams to play zone , since such defenses usually position a player in the middle of the key to stop penetration . The Dallas Mavericks under coach Rick Carlisle are an example of an NBA team that have regularly used zone defenses . </P>
when did the nba start playing zone defense
the 2001 -- 2002 season