📏 FIBA Article 33: The Geometry of the Cylinder
In modern basketball, no rule causes more intense debate among spectators, coaches, and players than the **Cylinder Principle**. Defined comprehensively in FIBA Official Basketball Rules Article 33, every player on the court is entitled to the space inside an imaginary cylinder extending vertically from the floor to the ceiling.
The cylinder boundaries are strictly defined:
- Front: By the palms of the hands and outstretched forearms (kept in normal basketball position).
- Rear: By the buttocks.
- Sides: By the outer edges of the arms and legs.
- Top: Extends infinitely straight upwards (verticality principle).
If an offensive player jumps forward into a defender who jumped vertically within their own cylinder, the contact is the legal responsibility of the offensive player, resulting in an offensive foul. Conversely, if a defender angles their arms forward (less than 90°) to contest, they have exited their cylinder and commit a defensive foul upon contact.
🛡️ The Restricted Area Arc: Why Was It Created?
Before the introduction of the semi-circular arc under the basket, secondary defenders routinely stood motionless directly beneath the rim to undercut driving players, creating dangerous mid-air collisions.
Both FIBA (1.25-meter radius) and the NBA (4-foot radius) instituted the **Restricted Area (RA)** rule. If a secondary defender has any part of either foot touching the arc line or hovering within the semi-circle, they are disqualified from drawing a charging foul against an airborne driver. Even if their feet are set and their arms are straight, the collision is ruled an automatic defensive blocking foul, protecting airborne finishers.
📊 Key Rule Differences: FIBA vs NBA
| Rule Element | FIBA / EuroLeague | NBA | Strategic Impact |
|---|---|---|---|
| Ball on Rim (Goaltending) | Legal to swat once it hits rim | Illegal; ring cylinder protected | FIBA centers can tip offensive rebounds off the iron |
| Restricted Area Radius | 1.25 meters (4.10 ft) | 4.0 feet (1.22 meters) | Slightly larger protection zone in international play |
| Defensive 3 Seconds | NO restriction (Zone legal) | YES (Technical free throw) | FIBA centers can park permanently in the paint |
| Offensive Rebound Reset | 14 seconds | 14 seconds | Both leagues unified to accelerate game pace |
Frequently Asked Questions
What is the Cylinder Rule in basketball?
The cylinder rule defines an imaginary vertical column occupied by a player. A defender has the right to jump vertically inside this cylinder, and any contact caused by an airborne shooter jumping forward is an offensive foul.
How does the Restricted Area Arc affect charging calls?
If a secondary help defender's foot touches or hovers inside the restricted area arc, they cannot draw a charging foul on a driver; the whistle is an automatic blocking foul against the defender.
Can players touch the ball on the rim in FIBA?
Yes. Under FIBA rules, once the ball touches the rim, it is live and can be tapped into the basket by offensive players or swatted away by defenders. In the NBA, the cylinder above the rim remains protected.
What is Legal Guarding Position (LGP)?
Legal Guarding Position requires a defender to face their opponent with both feet on the floor in a normal defensive stance before the offensive player begins their upward shooting or jumping motion.