DeCourcey became the Liberal Party's candidate in Fredericton during the 2015 federal election, and won, ousting
Conservative incumbent and former cabinet minister
Keith Ashfield. DeCourcey was appointed to the House of Commons
Special Committee on Electoral Reform, which was established due to the campaign promise made by the Liberal Party that 2015 would be the last federal election decided under the first-past-the-post system. That committee travelled across Canada in 2016 to consult with Canadians as to their preference for electoral reform, and in doing so, heard widespread support for a switch from the first-past-the-post electoral system to proportional representation. The Liberal government ultimately refused to table any legislation to enact electoral reform. In spring 2018 DeCourcey was criticized for violating House of Commons rules by using his taxpayer-funded newsletter to recruit volunteers for the Liberal Party. He was defeated in the 2019 federal election by
Jenica Atwin of the
Green Party. ==Career after electoral politics==