When teaching students about federal statutes, one of the most confusing concepts can be that of positive law. If there is a discrepancy between the Statutes at Large and the United States Code, the Statutes at Large trumps unless the title has been enacted into positive law, which has not happened with the majority of titles. Peter LeFevre of the Office of the Law Revision Counsel recently blogged about pending legislation that would solve many of the problems that now exist in the United States Code in Positive law codification will modernize U.S. code.
For some interesting reading about intricacies of the United States code and the problem of positive law see The United States Code, Prima Facie Evience, and Positive Law, Are You Positive About Positive Law?, The U.S. Code, the Statutes at Large, and Some Peculiarities of Codification and Positive Law Codification in the United States and other sources listed on the Law Librarians Society of D.C. website.