Available on eBay:  Mortimer Caplin IRS Commissioner Signed Autograph:

This is an authentic hand signed item and is NOT a preprint.  Buy It Now price:  $9.99.

From Wikipedia:

First in his class at University of Virginia School of Law, and Editor-in-Chief of Virginia Law Review, Caplin served as a law clerk to U.S. Circuit Judge Armistead M. Dobie. He then practiced law in New York City from 1941 to 1950, with time out for military service in the United States Navy. …  In 1950, Caplin returned to UVA as professor of law, specializing in tax and corporate law and publishing extensively in these fields. …  Following President John F. Kennedy's election, Caplin … in January 1961 was appointed Commissioner of Internal Revenue. …  Caplin remained at the IRS until July 1964 when he resigned to form the law firm of Caplin & Drysdale.