After Hurricane Katrina, Royce immersed himself in rebuilding his community by serving as chief of staff to former New Orleans City Councilmember James Carter. He then moved to Washington, D.C. to attend Howard University School of Law, where he founded the Howard Energy and Environmental Law Society to advocate for environmental justice. He also worked as an intern at the Environmental Protection Agency and the White House Council on Environmental Quality. After serving as a law clerk for Judge Thomas J. Motley on the Superior Court of the District of Columbia, Royce returned home to practice energy law with a multinational law firm.

As special counsel for former Chief Justice of the Louisiana Supreme Court Bernette Johnson, Royce championed criminal justice reform after observing the human impact of inefficiencies and inequities in our criminal justice system. He worked to change the system by spearheading the management of a half-million-dollar grant to develop and adopt better practices for assessing and collecting court costs, fines, and fees. In addition, he fought to protect and preserve the character of New Orleans’ historic neighborhoods as chairman of the New Orleans City Planning Commission, while nurturing social innovation and improving the quality of life for all residents. Royce now has his own legal practice, Duplessis Law Firm, he has had many successes primarily focusing on civil litigation.

Since 2012, Royce has volunteered as a mentor to male teenagers through the nationally-renowned Silverback Society. He is a past president of the Louis A. Martinet Legal Society, Inc., and used his presidency to increase the society’s commitment to legal access by conducting numerous free legal services and outreach clinics across New Orleans. He is also the co-founder and past president of the A.P. Tureaud, Sr. Legacy Committee, with the mission to honor the legacy of preeminent Louisiana civil rights attorney, A.P. Tureaud, Sr., and to educate the public about the remarkable contributions of other social justice heroes.

Royce is married to Krystle Ferbos Duplessis, and they are proud parents of one daughter, Reese. They reside in Central City.

Royce's leadership, dedication to the community, and public service have been recognized by the Louisiana Fair Housing Action Center (2022 Mondale-Brooke Award), Louisiana Center for Development and Learning (2021 Legislator of the Year), the E Pluribus Unum Fund (2021 Fellow), the Childcare Association of Louisiana (2019 Legislator of the Year), and the New Orleans Regional Leadership Institute (2017 Fellow; Leadership Award Recipient). He was also honored as one of Xavier University of Louisiana’s 2015 40 Under 40, is a member of the Education Leadership Institute (2016 Fellow), and the New Leaders Council (2014 Fellow). In 2012, Royce was elected to serve on the Orleans Parish Democratic Executive Committee.

In March of 2023, Royce was awarded the Calogero Champion of Justice Award for his commitment to youth justice, his partnership with Louisiana Center for Children's Rights at the state legislature, and his tireless efforts to make his community a better and more just place.

Royce is currently serving on the Board of the Innocence Project and Governor's Council on the Success of Black Men and Boys; demonstrating his commitment to Criminal Justice Reform and the marginalized.