The judge acquitted Ponyboy in the case is closed
The Monroe Doctrine was an effort to stop Europeans from influencing politics within the United States. (Lets say if Russia tried to turn the U.S communist during the cold war. The Monroe Doctrine would take into effect)
In "death, be not proud." the speaker is addressing his words to "death" himself, whom the author is trying to convey as a jealous and generally bad person.