In the early 1980s, Mac Cionnaith was jailed for six years for his involvement in the IRA bombing of Portadown's town centre.
[1] From 1997, Mac Cionnaith was the spokesman for the Garvaghy Road residents in the Drumcree conflict, which centres on the desire of the Orange Order to walk a traditional route through an area that had become predominantly Roman Catholic.
[citation needed] Mac Cionnaith continues to serve as spokesman for the Garvaghy Road Residents Coalition and, in February 2010, he helped formulate a joint submission to the Northern Ireland Assembly's Working Party on Parading Issues.
Mac Cionnaith has been critical of the Orange Institution and of the Royal Ulster Constabulary (since replaced by the PSNI).
[6] Mac Cionnaith joined the socialist republican political party Éirígí, and was elected General Secretary of the organisation in May 2009.