What is interference in horse racing?

The rules of racing require horses and riders to maintain straight paths unless clear of other runners and generally prohibit dangerous conduct.

The rules vary from jurisdiction to jurisdiction, but in the U.S. and Canada they allow racetrack stewards to disqualify runners who they deem to have interfered with a rival and place the offender behind that horse in the final order of finish if they determine the incident cost the other a better placing. Horses also can be disqualified if their riders engage in “willful” or “careless” conduct during a race, including striking an opponent or its rider with their crops.

In one recent high-profile disqualification, the colt Maximum Security was disqualified after crossing the finish line first in the 2019 Kentucky Derby for interfering with multiple rivals when he suddenly shifted outward entering the stretch. Stewards at Churchill Downs placed Maximum Security 17th in the order of finish, one spot behind Long Range Toddy, one of the horses that were affected by the incident.

Because of inconsistency in how disqualifications are meted out, some critics have called on the U.S. and Canada to adopt what the International Federation of Horseracing Authorities (IFHA) calls Category 1 rules, which give the stewards leeway to leave the placings unchanged if they determine that the horse interfered with would not have finished ahead of the horse causing the interference irrespective of the incident.

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