The NBA Allows the Zone
2001 to 2002 season. Illegal defense rules are scrapped
Before 2001, NBA rules banned zone defense. The "illegal defense" guidelines were meant to keep defenders matched up with players, but they had become so complicated that officials, coaches and fans struggled to follow them. Scores were lower, TV ratings were falling and attendance was flat.
On 19 April 2001, the NBA's owners voted 22 to 6 to scrap the illegal defense rules from the 2001 to 2002 season. Zone defense was now legal. To stop teams parking a center under the basket, a new defensive three-second rule said a defender could not stay in the lane for more than three seconds unless closely guarding an opponent. Teams also got 8 seconds, not 10, to bring the ball past half court.
Suns owner Jerry Colangelo called it possibly one of the most significant changes since the 24-second shot clock. Not everyone agreed it would help: Orlando coach Doc Rivers predicted less scoring, not more.
What changed
Defenses could now send help toward the ball without breaking a rule, so a single star going one on one became easier to stop. Offenses had to move the ball and space the floor to make that help defense pay.
In the Dictionary: Box and One, Help, Triangle and Two