This is an example of a Defensive 3 Seconds Violation. Defensive 3 Seconds is called when a defensive player, who is positioned inside the 16 foot key area, does not actively guard an opponent within three seconds. The highlighted defender on this play appears to move to double team the offensive player, but he does not legally achieve this position as he aligns hilmself directly behind his defensive teammate. Because a defensive player cannot legally actively defend an opponent from behind a teammate, and because he remains in the key beyond the allotted three seconds, the play is ruled a Defensive 3 Second Violation.