As a young man he was one of the original organisers of the
Derry Housing Action Committee (DHAC), a radical campaign group focusing on access to social housing. DHAC organised, in conjunction with the
Northern Ireland Civil Rights Association (NICRA), the second civil rights march in Northern Ireland. This march, which took place on 5 October 1968, is generally seen as the birthdate of the
Northern Ireland Civil Rights Movement. His political contemporaries included
Bernadette Devlin, for whom he served as an election agent. He stood for election in the
Foyle constituency at the
1969 Northern Ireland general election for the
Northern Ireland Labour Party, placing third with 1,993 votes (12.3% of the total). He was tried (as one of the so-called
Raytheon 9) in Belfast in May–June 2008 over alleged damage caused during the
2006 War on Lebanon to a facility operated by multinational arms company
Raytheon in Derry. The jury unanimously acquitted McCann, and all the other defendants, of charges of criminal damage to property belonging to Raytheon. The jury had heard that the group's actions were prompted by repeated bombing of Lebanese property in which numerous civilians died, and the wish to protect those lives and that property from being attacked by Israeli forces with weapons, weaponry systems and missiles supplied by Raytheon. The judge dismissed charges of
affray after hearing the prosecution evidence. However, McCann was convicted of the theft of two computer discs, for which he received a 12-month conditional discharge. In a statement outside the court, McCann said: "[We] have been vindicated. ... The jury have accepted that we were reasonable in our belief that ... Israeli ... Forces were guilty of war crimes in Lebanon in the summer of 2006. The action we took was intended to have, and did have, the effect of hampering or delaying the commission of war crimes". McCann explained that her family had asked him to speak at her funeral. He said: "I don't think I said anything at Dolours Price's grave that contradicted that [calling McConville's murder 'a horrible and unforgivable act'] ... The point I had in mind, the point I was making, was there are some people deeply implicated in the cruel murder of Mrs McConville who appear not to be undergoing any inner turmoil. They appear to find it very easy to handle the knowledge of their own involvement in that murder". He was elected as an
MLA for
Foyle in May 2016 but lost his seat in January 2017 when the number of seats in the Foyle constituency was reduced from six to five. McCann and People before Profit attracted criticism from
Sinn Féin and pro-EU activists for supporting
Brexit in an area with the fourth-highest 'Remain' vote (out of approximately 400 counting areas) in the whole of the United Kingdom. In May 2019 he was elected to
Derry and Strabane District Council as a PBP candidate in The Moor electoral area. In March 2021, he announced his resignation from the council for health reasons. ==Campaigning work==