This COTH article contains this information:
"At the Competition Open Forum, the committee discussed the newly implemented USEF rule DR.126, which went into effect on Dec. 1. It requires a competition’s technical delegates to visually check bits and bridles of 50% of the horses entered in competition by walking through the stables and examining equipment. At Level 1-3 shows, this new procedure will eliminate the need for equipment checkers to use their fingers to assess the legality of the bit in the horse’s mouth. At Levels 4-5, officials will go into the mouths of horses to check equipment.
Lisa Gorretta, co-chair of the U.S. Equestrian Federation Dressage Sport Committee, explained that the difficulty of finding enough licensed officials to check equipment and concern for the safety of checkers who have to use fingers to check bits inside the horse’s mouth as the impetus for the rule change. A show’s individual competition management and technical delegates will be provided with procedure sheets to decide how they will manage the equipment checks, and they are expected to send out that information to competitors."
The actual rule doesn’t mention anything about the TD going into the stabling so I wonder how this will work. Couldn’t someone just switch the bit from whatever they had on their tack hook to something else…?