DePhillips earned a bachelor of arts degree with a major in government from Georgetown University in 1987 and a juris doctor degree from Seton Hall University School of Law in 1992. From 1987 to 1989 he worked in Washington, D.C. as an aide to Congresswoman Marge Roukema. A practicing attorney, DePhillips is Vice President and General Counsel of Porzio Life Sciences. A member of the Wyckoff Township Committee from 2010 to 2013, DePhillips was unanimously chosen by his peers to serve as the township's mayor in 2012. Appointed in June 2012, he served until 2017 as a Commissioner of the Northwest Bergen County Utilities Authority, which provides sewage treatment services to 75,000 residents in Bergen County.
In the 2019 General Election Democrats Maria Martini Cordonnier, and Micheal Sedon won the primary to challenge DePhillips and his running mate Kevin J. Rooney. However Sedon dropped out of the general election and was replaced with former Bergen County Freeholder Julie O'Brien. During the election DePhillips and Rooney skipped a debate hosted by the League of Women Voters claiming it was unfair. The democrats lost to the incumbents. Rooney came in first place in Bergen, Passaic, Essex, and Morris Counites.
2017
In the 2013 general election, the last time all three legislative seats in the 40th District were up for vote simultaneously, the winners were Kevin J. O'Toole in the Senate and Scott Rumana and David C. Russo in the Assembly. By the 2017 primaries all would be gone, with O'Toole resigning in 2017 to become a Commissioner of the Port Authority of New York and New Jersey, Rumana leaving in 2016 to become a Superior Court Judge and Russo's announcement that he would not run for another term of office, leaving a vacuum that led to a series of primary challenges. In the June 2017 Republican primary for the two Assembly seats, Rooney and DePhillips withstood a challenge from Joseph Bubba Jr. and the comeback attempt of former State Senator Norman M. Robertson by margins of 2-1; Kristin Corrado won the Senate nomination against former Assemblyman Paul DiGaetano. Since 1973, the 40th District has always leaned Republican, never electing a Democrat through the 2017 general election. However, a poll conducted by Democrats shortly before the election showed the two slates tied at 39%, with 21% of voters undecided. In the November 2017 general election, DePhillips and his running mate, incumbent Kevin J. Rooney, defeated Democratic challengers Christine Ordway and Paul Vagianos to win both Assembly seats from the district for the Republicans.
