After completing a PhD in English at the Queen's University of Belfast, he taught at St Patrick's Grammar School in Downpatrick. He left teaching to become Town Clerk of Downpatrick the then administrative centre of County Down, succeeding his father in the role.
In the troubled politics of Northern Ireland, where political parties tend to be sharply split along pseudo-ethno-nationalistic lines, Hayes has been viewed as an even-handed observer, who has written or contributed to major policy reports, such as the Patten Commission dealing with reforms to the Royal Ulster Constabulary (RUC), the police force later renamed the Police Service of Northern Ireland (PSNI).
He has written numerous pieces of journalism and writes regularly for the Irish Independent. He is the author of three books of memoirs, Sweet Killough: Let Go Your Anchor; Black Puddings with Slim: A Downpatrick Boyhood; and Minority Verdict: Experiences Of A Catholic Civil Servant. He is also the author or editor of works on conflict research, community relations and Irish writing.
He is a member of the Royal Irish Academy and the Research Ethical Committee of Queen's University Belfast medical school, and a governor of the Linenhall Library, Belfast. He is a long-serving member of the Scholarship Board of the O'Reilly Foundation. He is also a board member at Regtel.
Hayes was asked by Mary Harney, when she was the Minister for Health in the Republic of Ireland, and the HSE (the Republic's Health Service Executive) to conduct a review into a scandal in the radiology department at Tallaght Hospital on the outskirts of Dublin.
Hayes is a former Northern Ireland Ombudsman and Boundary Commissioner, and was Permanent Secretary of the Department of Health and Social Services. He is a former chairman of the Community Relations Council and the Acute Hospitals Review Group.
He was chairman of The Ireland Funds in the Republic of Ireland, a branch of a major charitable group with worldwide contributors, which has made significant grants to groups dealing with social and business problems.
Hayes was also a long-serving non-executive director of Independent News & Media Plc, retiring in 2009 towards the culmination of a long running battle for control of the group between the O'Reilly family and Denis O'Brien led to a re-structuring of the Board.
He also served, at the Taoiseach's request, as Chairman of the National Forum on Europe in the Republic of Ireland. The approach he devised to educate the population on the arguments over European issues was so successful that many other European countries adopted similar methods.
Hayes was voted European Person of the Year in 2003.
He has also received honorary doctorates from his alma mater; from both Queen's University Belfast and University of Ulster in the UK, as well as Trinity College, University of Dublin and National University of Ireland in the Republic of Ireland.
Hayes is a former county hurler, who in the mid-1950s became County Secretary of the Down Gaelic Athletic Association (GAA) and set a ten-year plan for the county Gaelic football team to become the first team from Northern Ireland to win an All-Ireland football final. Within five years, Down had won their first All Ireland trophy in 1960. They followed it with further successes in 1961, 1968, 1991 and 1994. With talent in the sixties such as Paddy Doherty, Joe Lennon and James McCartan Senior (whose son, James Jr, went on to win the All Ireland with Down in the 90s), Down should have won more All Ireland titles. No other Northern team won an All Ireland title until Derry won the All Ireland football title in 1993, since when Northern Irish teams have dominated the football championship. In 2010, the Down team, under its coach James McCartan, fought its way to another All Ireland final after defeating Kerry and Kildare to set up a clash with Cork. The defeat of Kerry was the fifth straight championship victory for Down over their experienced rivals. It followed a debate about whether Down should retain its style of attacking football, and Hayes was one of those who argued for retention of the 'Down way' of playing. Down lost the 2010 final by one point.
- "Dr. Maurice Hayes". Oireachtas Members Database. Retrieved 26 May 2010.