An official's No. 1 job is to call fouls and rules infractions during the game. In the NBA, a player who collects six fouls must leave the game and can not return. For college and high school, the foul limit is five. Nothing alters a team's strategy more dramatically than when a player gets into early foul trouble or a violation halts a team's play. Referees call all violations, such as traveling (walking without dribbling the basketball), and fouls, such as blocking (obstructing an offensive player's momentum without setting your feet). In live game action, though, it is a challenge to break down plays quickly, often resulting in judgment calls--sometimes right, sometimes wrong--by the referee. In the NBA, league executives review officials at a team's request if the team feel calls were purposely going against it. In that case, a referee may face consequences such as suspension.
Digital clocks keep track of game time on the court during play (four 12-minute quarters in the NBA, two 20-minute halves in college, four eight-minute quarters in high school), but they can always malfunction. In such cases, the referee will be asked to keep time with a stopwatch. The referee must also watch the shot clock and make sure no offensive player gets a shot off after the clock expires.
With the introduction of instant replay to the NBA, a referee must also assess replays on a court-side monitor. These can vary from judging whether a player got a shot off in time before the final buzzer or if the clock manager at the scorer's table failed to start up the clock at the right time. In such cases, a referee will review footage, then make a quick decision to count a basket or reset the clock to the correct time. Although there is no instant replay on the high school level as of 2010, refs calling an NCAA game can only review certain plays, such as if a shot should be scored a 2- or 3-pointer. NCAA refs can only review buzzer-beaters if they come at the end of a half or overtime periods.
Officials must act as zero-tolerance disciplinarians on the court. Keeping athletes and fans safe is a top priority. A soft nudge after the whistle can quickly turn into a hard push and then a punch. To curtail trash talking and overaggressive behavior refs can issue a technical foul--the most damaging personal foul call in the game. Not only does the violator get charged a personal foul at the college and high school level, but the other team gets possession of the ball and free throws.