Editors' Summary: Last year, the Library of Congress released the papers of the late U.S. Supreme Court Justice Harry A. Blackmun. In so doing, it provided scholars with access to a remarkable record of the Court's inner workings. Among the Blackmun papers is an extensive collection of letters, memoranda, and draft opinions that the Justices exchanged during the most formative period of environmental law. The author, a former law clerk to the late Justice Byron White and the Director of the Environmental Law Program at the University of Maryland, reviews highlights from those papers and what they reveal about the Court's handling of environmental cases during Justice Blackmun's service on the Court from 1970 to 1994. The author also analyzes what the Blackmun papers reveal about challenges to environmental regulation in three areas in which the Court under Chief Justice William H. Rehnquist has had great impact: federalism, regulatory takings, and environmental standing. The author then discusses what the papers show about relations among the Justices and public scrutiny of the Court's work. The author concludes with some thoughts on the Court's role in shaping environmental law.