A hearing Monday follows a jury verdict last month that said the American Quarter Horse Association's prohibition against registering clones violated state and federal antitrust laws.
The case is being watch closely by other U.S. horse-breeder groups because none currently allow cloned horses to be registered.
U.S. District Judge Mary Lou Robinson could rule quickly based on briefs filed last week by both sides' attorneys or she could ask for additional argument.
The two breeders who filed the lawsuit argued that the association was operating a monopoly by excluding clones.
The quarter horse association says it will work to overturn the verdict and will appeal if Robinson rules to allow registration of clones.
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