From BR Bullpen
The official scorer is the official arbiter of scoring decisions. The official scorer sits in the press box, views the action, communicates decisions, and keeps the official scorebook (see scoring a game). The scorer is appointed by the league office.
Official scorers are often sportswriters. Their primary responsibility is deciding whether a player reached base as a result of a fielding error or if the batter would have made it to first base regardless of the fielder's actions. The decision whether a pitch is a wild pitch or a passed ball also lies with the official scorer.
The official scorer is also responsible for awarding a win when the rules dictate that a win needs to be awarded. The scorer also keeps track of games played under protest or games that are suspended. He or she should make a note of the time and situation of the protest or suspension.
At the conclusion of the game, the official scorer is responsible for reporting to the league office the official score report and proving the box score. It is then transmitted to the league office to keep official statistics.
On occasion, an official scorer will ignite controversy during a no hitter as the decision whether a batted ball is a hit or an error lies with the scorer. One well known incident occurred in 1968 when Roberto Pena bobbled an easy grounder hit by Jeff Torborg. Scorer Phil Collier scored the ball a hit. The pitcher for the Phillies, Rick Wise, did not give up another hit and lost a no hitter due to Collier's ruling.