Rodney's lawyer believed that his trial court made a mistake about a question of law pertaining to his case. because this sometimes happens, the american legal system allows?

Because what happened with Rodney sometimes happens, the American legal system allows appeals.

Explanation:

If a judgment given by a lower court is not acceptable to the defendant and his lawyer, they can choose to appeal in the higher court against the decision of the lower court. The higher court can either accept to hear the case or can return back to the lower court with an order to hold a few more proceedings for reconsideration.

It could help to protect other English colonies.