Goaltending, basket interference and the imaginary cylinder
Rules2 min read
When a defender is allowed to touch the ball near the rim, when he is not, and why the ceiling above the ring is treated as a solid space.
Above every ring there is an imaginary cylinder, the same diameter as the ring, rising upward. Once the ball is inside that cylinder, nobody from either team may touch it. Once a shot is on its way down toward the basket and above the level of the ring, a defender may not touch it either. Break the first rule and it is basket interference. Break the second and it is goaltending.
The consequence is the same in both cases: if a defender commits it, the attacking team is awarded the points the shot would have scored, two or three depending on where the shooter was standing. If an attacker commits it, the basket is cancelled and the defending team gets the ball.
The downward flight condition is the part that produces arguments. A block is legal as long as the ball is still rising, or as long as it is below the level of the ring. A defender who times his jump so that his hand meets the ball at the top of the arc, an instant early, has made a clean play. An instant late and he has handed over the points without a foul being called. At full speed the difference is invisible, which is why this is one of the calls that gets reviewed.
Two situations override the flight rule entirely. A ball that is touching the rim, rolling or bouncing on it, is protected: nobody may touch it or the net or the ring while it is there, because doing so changes the outcome mechanically rather than athletically. And a ball that has hit the backboard above the level of the ring and is heading toward the basket is similarly protected, in rule sets that include the backboard clause.
There is a corresponding offensive rule people forget. An attacking player who tips in a shot that is still inside the cylinder, or who hangs on the ring and touches the ball, has committed offensive basket interference and the basket does not count. Pulling the net or shaking the backboard to disturb a shot falls under the same heading.
Watching for it is easiest on rebounds rather than shots. When several players go up together and the ball is rolling around the rim, hands come in from all sides, and the whistle that follows is usually about the rim rather than about contact between players. The ball on the ring is untouchable until it falls off, one way or the other.