In his 1984 landmark article, Abstention, Separation of Powers, and the Limits of the Judicial Function, Professor Martin H. Redish advanced the thesis that the abstention doctrines constituted a violation of separation of powers. Redish’s theory was, and is, controversial. The suggestion that an embedded area of federal courts law is unconstitutional is, at the least, highly provocative. It is also ultimately unpersuasive. There are too many justifications underlying the legitimacy of abstention to support the conclusion that it violates the Constitution. Yet, as this Essay demonstrates, one does not have to be persuaded by Redish’s constitutional conclusion to appreciate the landmark significance of his project. Prior to Abstention, Separation of Powers, and the Limits of the Judicial Function, the virtues of judicial restraint had been reflexively characterized as judicial deference to the decisions of political actors. Professor Redish, however, replaced this understanding with the more nuanced view that judicial restraint might also mean courts performing the tasks to which they were assigned. In so doing, Redish fundamentally recast the debate as to the proper understanding of the role and obligations of the federal judiciary and the meaning of judicial activism and judicial restraint.