He received a Bachelor of Arts from Carroll University in 1973 and a Juris Doctor from the Duke University School of Law in 1977. He was a faculty member at Northwood University, where he taught business law, economics, and logic. He was later a vice-president at the John Locke Foundation and director of the Martin Center until the then-Pope Center became an independent nonprofit in 2003.
Leef is the author of Free Choice for Workers: A History of the Right to Work Movement and editor of Educating Teachers: The Best Minds Speak Out. From 1996 through 2012, he was the book review editor of The Freeman, a libertarian journal published by the Foundation for Economic Education. He has published articles and book reviews in The Wall Street Journal, Regulation,Christian Science Monitor,The Cato Journal, and other publications.