Rules Analysis
If the player against whom the foul, infraction or violation has been called disagrees that it occurred, they may call "Contest".
If the player against whom the foul, infraction or violation has been called disagrees that it occurred, or does not think it is a correct call, they may call “Contest”.
If, for example, the player against whom the breach was called thinks that the breach was not significant enough to make a difference to the outcome of the action, they can contest the call.