Why is Tull outraged with the decision about his case in the courtroom?

At the end of the trial, Tull is outraged to learn that Eck will not be forced to pay him any money as a result of the damages incurred by the wild horse stampede. As it turns out, there is an obscure law that states, "the ownership of a commodity is not transferred unless there is the exchange of some money or a written agreement," which means that since Hipps gave Eck the horse for free, Eck is not financially responsible for any of the damages from the horse stampede.