So, my roommate and I were arguing over the Temporal authority over kings and governments the Roman Pontiff claimed throughout history till Vatican II. They were claiming that the Church never really claimed authority to reject or command civil policy, only that they would influence things strictly for spiritual/Church matters. I was wondering if any of you could list for me examples of papal documents, ecumenical councils making declarations on the subject, because reading from the Syllabus of Errors wasn't enough to convince them. Would you have historical examples of the Pope/the Church exercising this authority?
You may find my three part answer to this question interesting. It covers much of the history of the papacy, with an emphasis on its relations with secular powers.
To briefly answer your question directly I would refer you to Dictatus Papae, a short 11th century document with a somewhat uncertain early history. It is connected with the Investiture Controversy, a conflict between the Pope and the Holy Roman Emperor over who held the higher authority. The document sets out the Pope's position, though it appears that it may not have actually been widely published at first. But if all you are looking for is a document claiming that the Pope's authority exceeds the Emperor's, look no further than point 12, "It may be permitted to [the Pope] to depose emperors," and point 27, "He may absolve subjects of their fealty to wicked men." Note, though, that while the Pope claimed this authority, that does not mean that it was ever actually recognized by kings and emperors. For a time when a Pope tried to assert authority over a powerful king, see my linked answer above. The story of Pope Boniface VIII vs King Philip IV of France illustrates the complexity of the relationship between church and crown.