<P> A defensive three - second violation, also known as illegal defense, is a basketball rules infraction in the National Basketball Association (NBA) introduced in the 1983 - 1984 season . It is assessed when a member of the defending team spends more than three seconds in the free throw lane (as well called the 16 - foot lane, or as otherwise known - "in the paint") while not actively guarding an opponent . To be considered actively guarding, a defender must be within arm's length of an opponent and in a guarding position . A three - second count is suspended if: </P> <Ul> <Li> a player is in the act of shooting </Li> <Li> there is a loss of team control </Li> <Li> the defender is actively guarding an opponent </Li> <Li> the defender clears the painted area </Li> <Li> it is imminent the defender will become legal </Li> </Ul> <Li> a player is in the act of shooting </Li>

What is the half court defence rule in basketball