I want to test the ability of students to read a passage and answer questions about it. Could you please come up with a good question for the passage "International tribunals and arbiters are often called upon to resolve substantial disputes over treaty interpretations. To establish the meaning in context, these judicial bodies may review the preparatory work from the negotiation and drafting of the treaty as well as the final, signed treaty itself."? 

What do arbiters use to make a decision?