Abraham Lincoln decided to issue the Emancipation Proclamation because of the failure of earlier proposals to end American slavery gradually, an idea that he had long supported. Historian Thomas Carson provides a careful reading of the document's text, explaining Lincoln’s earlier attempts to end slavery. He presents well-known criticisms of the Emancipation Proclamation and Lincoln’s reasons for doing what he did. The question of whether the proclamation was consistent with the law and the U.S. Constitution was something that greatly worried Lincoln.