'˜Supreme Court ruling could also affect republican processions'

The TUV leader, who is a qualified barrister and QC, said Wednesday’s decision – in favour of an unnamed Belfast resident who claimed the PSNI failed to stop illegal loyalist parades – may have left the PSNI with “no option” but to intervene.

Mass protests, some of which descended into violence, took place across Northern Ireland in opposition to Belfast City Council’s decision to limit the number of days the Union Flag flew over City Hall.

In April 2014, a judge at Belfast High Court ruled in favour of the resident of the nationalist Short Strand area, who claimed the failure to stop unnotified loyalist marches past his home between December 2012 and February 2013 breached his right to privacy and family life.

Later that year, appeal judges overturned the ruling following a challenge by the PSNI. The resident then took his case to the Supreme Court.

Mr Allister said: “In light of today’s ruling I look forward to the PSNI adopting a much more robust approach when it comes to illegal republican parades which glorify terrorism. All too often the PSNI stand by while the actions of terrorists who stole the lives of their fellow citizens are celebrated,” he said.

“I am mindful that in 2011 for example Martin McGuinness and Conor Murphy took part in an illegal parade at the infamous Ti Chulainn Centre in south Armagh. Moreover, if the Supreme Court is saying the police must always exercise their powers, then, I’m sure many innocent victims of terrorism look forward to thorough investigations of the crimes that made them victims.

“Teeban, Enniskillen, La Mon – the list is endless of atrocities where the powers of investigation have been parked and no active pursuit of the perpetrators is in place.”

SDLP justice spokesman Alex Attwood described the judgment as “very significant,” and said it will have “consequences for the police and others around parades and protests”.

Mr Attwood said: “The judgment is unambiguous. The PSNI had ‘an inescapable duty to prevent, where possible, what was plainly illegal’.

“The law is clear. The authority of the Parades Commission is clear. The acceptance of both by everyone is the best way to navigate through future parades and protests. No one should be found wanting – be it the public, the police or politicians.”

Sinn Fein councillor Mairead O’Donnell also welcomed the judgment.

She said: “Essentially the community was under siege from these illegal parades. The community challenged the PSNI to do something about it but they refused.

“The PSNI got it wrong and the community in the Short Strand suffered.”