Laplante worked in private practice in New Hampshire, from 1990 to 1993. He was a senior assistant attorney general in the Office of the Attorney General of the State of New Hampshire, from 1993 to 1998. He was a trial attorney in the Criminal Division of the
United States Department of Justice, from 1998 to 1999. He was an
assistant United States attorney in the United States Attorney's Office for the District of Massachusetts from 2000 to 2002 and served as first assistant United States attorney in the United States Attorney's Office for the District of New Hampshire from 2002 to 2007. Laplante was nominated by President
George W. Bush on June 13, 2007, to a seat vacated by
Joseph A. Diclerico Jr. and subsequently confirmed by the Senate on December 14, 2007 by a vote of 97-0, receiving his commission on December 28, 2007. He served as chief judge from 2011 to 2018. ==Other activities==