By the end of this decade virtually all fifty U.S. state legislatures will have debated, and many will have adopted, mandatory seat belt legislation. While the debate in the United States has just begun, one can anticipate and preview the issues, arguments, and results by examining the British debate over, and experience with, a mandatory seat belt law. From this cross-national perspective, this article examines the practical, philosophical, and preventive health care dimensions and implications of this debate. Based upon personal interviews and the Parliamentary record, the author traces the background of the issue, and the major arguments for and against mandating seat belt use. Particular emphasis is placed upon the libertarian objections to such legislation, and how some British Conservatives were able to reconcile their philosophical beliefs with public safety needs. The article concludes by suggesting some lessons which U.S. proponents of mandatory seat belt legislation might learn from the British experience.