The judge advised the jury to refer to the relevant statutes before making a decision.

refer 是动词，意思是"参考、查阅"，常与介词 to 搭配使用。 to 在这里是介词，表示动作的方向或对象。 refer to 是一个固定搭配的短语动词，意思是"查阅、参考（某资料）"。