Top of the Key: Basketball Court History and Rules

The key in basketball is an area of the court that extends from the free throw line, or foul line, to the baseline, or endline. The baseline is the boundary line that runs along the edge of the basketball court, behind the backboard of the hoop, and determines when a ball is out of bounds. Bordering the key are sidelines that mark the boundaries of the court; they typically feature a different color than the rest of the court.

Depending on the game’s level of play, the key also goes by several other basketball terms: The National Basketball Association (NBA) and National Collegiate Athletic Association (NCAA) refer to the key as the “free throw lane,” while FIBA, which is the game of basketball’s international governing body, calls it the “restricted area.” The key also has informal monikers such as “paint” and “lane.”

The key derives its name from its original shape: a six-foot-wide lane that culminated in the free throw circle and resembled a key used for locks or doors. However, the size of the key allowed tall basketball players like six-foot-ten-inch George Mikan to dominate the game. In 1951, the NBA resized the key from six feet to twelve feet. The league later added a foot in 1964 for a total width of sixteen feet, due largely, again, to powerful centers like Wilt Chamberlain.

Today, the level of play defines the size and shape of the key. The NBA’s key is a sixteen-foot-wide, rectangular area; the NCAA and National Association of Intercollegiate Athletics (NAIA) use a twelve-foot, rectangular key. FIBA keys were trapezoidal in shape until 2010 when FIBA adopted a sixteen-foot-wide, rectangular design.

The top of the key rests above the top-most point of the free throw circle, a twelve-foot circle bisected by the free throw line, which ends at both corners with the high post and below the half-court line. The three-point line extends from either side of the top of the key. It’s an ideal location to call offensive plays because of its mid-court location in the front court, or the location of the offense’s basket (the backcourt houses the defense’s basket). Once the point guard brings up the ball to the top of the key, the offense can balance the court by distributing offensive players to both the strong side of the court—the side with the ball handler—and the weak side.

Although point guards often call plays at the top of the key, it’s a suboptimal place to attempt a field goal or three-point shot. The top of the key is the point furthest from the basket for a two-pointer, and statistics have shown that three-point shot attempts from the corner are more successful than two-pointers made at the top of the key.

The top of the key is also where half-court games begin. Unlike full-court games, half-court games do not use a jump ball to determine possession of the ball. Instead, offensive and defensive players start the game by checking the ball: The ball handler stands at the top of the semicircle above the free throw line and says, “Check,” while passing the ball to the player on the opposing team that’s guarding them. When the defender passes the ball back to the offense, the ball is inbounds, and the game begins.

A three-second violation, which is also known as a “lane violation” or “three in the key,” is a ruling against a basketball player who remains inside the key for more than three seconds. There are two iterations of the three-second rule:

1. 1. Defensive three-second violation. Also known as illegal defense, a defensive three-second violation is a team technical foul given when a defensive player spends more than three seconds in the key while not guarding an opponent. As stated in the NBA rulebook, the offense receives a free throw and possession of the ball due to this foul. The defensive three-second rule makes it difficult to run a zone defense, which is a strategy that assigns defensive players to cover specific areas of the court. The defensive three-second violation doesn’t apply to FIBA or high school basketball games.
2. 2. Offensive three-second violation. The offensive three-second violation is similar to the defensive variation. A referee will call this foul on an offensive player who remains in the key while the player’s team is in control of the ball and fails to make a shot, or passes or dribbles out of the lane. The purpose of the offensive three-second violation is to prevent offensive players from lingering near the low post while the shot clock is running, which would allow for limitless rebounding, blocking, and layup attempts.

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