Numerous times, when asked what persuaded him to make his decision to enter power-sharing with Sinn Fein, Ian Paisley said that republicans’ support for the police convinced him that the party had fundamentally changed.
More important even than decommissioning of IRA weapons, it was republican support for the PSNI which in the DUP veteran’s eyes showed the party had turned its back on the past and had the potential to usher in a new era of stability.
Although now retired from politics and no longer needing to explain his decisions to the public, if Lord Bannside was listening to senior Sinn Fein figures over the last 36 hours, he must have winced somewhat.
When the crunch came, and the police came for Sinn Fein’s president, any pretence at a support for due process or argument to the republican community that the police, prosecutors and the courts can be trusted to deliver justice vanished.
In a development which will have reinforced many unionists’ belief that Sinn Fein’s support for the police is self-serving, the party denounced Mr Adams’ arrest as “politically motivated”.
No evidence was given to support an accusation which, if true, would be constitutionally explosive in any democratic society.
And the party’s claims of “securocrats” or “dark forces” within the institutions of law and order are increasingly difficult to sustain.
The current chief constable was the first to be supported by Sinn Fein; in fact, Alex Maskey was on the panel which gave Matt Baggott the job. In coming weeks, Gerry Kelly as Sinn Fein’s current representative on the Policing Board, will interview candidates to succeed him as chief constable.
The claim of ‘political policing’ — a variant of which seems to be made any time an individual connected to Sinn Fein is investigated by police — is all the more extraordinary because of the party’s recent stance on policing south of the border
In the Republic of Ireland, where Sinn Fein’s focus is increasingly centred, the party has recently been pushing for a Policing Board-style political body to oversee the Garda, which is reeling from a series of scandals.
If Sinn Fein’s presence on the Policing Board has been so ineffective that the force is being run along such virulently anti-Sinn Fein lines that its leader is arrested for no reason other than to damage the party, it would be odd in the extreme to advocate such a flawed system for the Republic.
However, although the police are currently in Sinn Fein’s sights, if a decision is taken to charge Gerry Adams, it will be taken by the Public Prosecution Service, which is headed by Mr Adams’ former solicitor, Barra McGrory.
Mr McGrory has made clear that he will not involve himself in any decisions about his former clients.
Nevertheless, if a decision is taken to charge Mr Adams, it would be a stretch for Sinn Fein to credibly claim that an organisation headed by Mr Adams’ former legal representative was acting politically to damage Sinn Fein.
The logic of Sinn Fein’s recent trajectory away from a violent opposition to the state is that it must support the police and the courts, however unpalatable that may be.
Where once Sinn Fein was the radical outsider, it is now a firmer part of the new Northern Ireland establishment than many other political parties. But only in an undemocratic and totalitarian regime does being a part of the political establishment equal immunity from investigation by the police.