He is formerly a Catholic priest and formerly a member of the Society of Jesus (the Jesuits). A fellow Jesuit, Fr. Robert Drinan, SJ ran successfully for Congress in 1970 in Massachusetts without being expelled from the order. McLaughlin then sought to do the same for the Senate in Rhode Island and lost the election. He then took a job in the Nixon White House, and ordered by the Jesuits to return to Boston, he resigned from the order.