Experimental psychology finds an effect called the omission bias, where acts of omission are viewed as far less harmful or intrusive than acts of commission, even if the outcomes are the same or worse.  We apply this idea to referees across five different sports and 10 different professional leagues, including MLB, the NBA, the NFL, the NHL, and the six largest European soccer leagues.  We find systematic evidence that officials routinely exhibit the omission bias by trying not to insinuate themselves into the game.  This results in referees making far more incorrect non-calls than incorrect calls.  Moreover, when the game is on the line (e.g., close scores near the end of a game), officials step back even further, in an attempt to remove themselves from the game, resulting in even more incorrect non-calls.  We show evidence of this pattern across all sports in all leagues we examine.  Furthermore, we also find evidence that when incorrect calls are made, and especially the more obvious the mistake, referees typically and immediately make another incorrect call for the other team (the so-called "make up" call).  We interpret this evidence as consistent with the bias to not influence the game by trying to balance out known or perceived blown calls.