May a treaty violate an international law?

I wonder if my classmates in Statutory Construction under Prof. Jennie C. Aclan, and in Legal Writing under Prof. Gallardo Escobar, may agree. But I find something imprecise in this question in the 2008 Bar Examinations in Political Law:

     May a treaty violate international law? If your answer is in the affirmative, explain when such may happen. If your answer is in the negative, explain why. (5%)

The imprecision stems from the word "may".  According to the Cambridge Online Dictionary there are several ways that may is used in American English:

And thereby hangs the dilemma were I an examinee.

Is the question about possibility? Then my answer should approximate the suggested answer given in Answers to Bar Examination Questions in Political Law (1987-2010) edited by Eduardo A. Labitag and published by the U.P. Law Complex.

Here's how Ralph A. Sarmiento paraphrased the answer on page 16 of his reviewer Public International Law, Bar Reviewer, 20016 Edition:

But what of the student  who, in a stat con class, has been steeped in the dictum that the word may means that a legal precept is permissive? He or she will be more naturally inclined to take the negative side and argue that a treaty cannot be permitted to violate international law.

There goes the 5%.


In questions like this my only hope is the annual guideline to the Bar Exams put up by the Supreme Court: