Go to the scorecards
Go to the scorecards means that, if a bout goes to its scheduled number of rounds, the winner, if any, is determined by the judges' scores.
It also refers to the rule that, if there is an accidental headbutt during a bout, it will go to the scorecards to determine the winner, if four rounds of a scheduled 12-rounder have been completed. Otherwise, the bout will be declared no contest.
See also, Unified Rules of Boxing