Sighinolfi was born in Chicopee, Massachusetts and is a graduate of St. Anselm College, Trinity College and Columbus School of Law at Catholic University of America.

He co-authored Maine Employer’s Guide: Worker’s Compensation. He is a member of the board of editors and contributes to Maine Business & Employment Law, a publication of Northern New England Law Publishers. In 1995, he was appointed by the Board of Overseers of the Bar to serve on Panel A of the Board’s Grievance Commission.  In 1997, he became Chair of the Panel, a position he held until 2002 when he was precluded by term limits from further service.

The Maine Supreme Judicial Court appointed Paul to a three-year term on the Board of Overseers of the Bar in November 2002.  He was reappointed for a second three-year term in 2005 where he served as the Vice Chair of the Board.  Paul was appointed Chair of the Board of Bar Overseers by the Supreme Judicial Court on November 1, 2007, and on November 1, 2008 he was precluded by term limits from further service. In December of 2009, the Maine Supreme Court appointed Paul as a trustee of the Lawyers Fund for Client Protection. He still serves in that capacity.