Numeromancer suggested that you rewrite your sentence which uses "suppose" in passive voice, into active voice.

It is a school exercise at least in some European countries. It is a syntactic transformation of the sentence. Depending on the verb and other factors, the transformation preserves meaning, but sometimes it brings up a subject which was not clear in the original sentence in passive voice.

Thus, Numeromancer is suggesting a way for you to reflect on the scope of authority by using a syntactic transformation.