The findings of the Smithwick Tribunal have served to cast a chink of light into another dark aspect of the Troubles that destabilised Northern Ireland for the best part of 30 years.

In a report that runs to more than 500 pages, Judge Peter Smithwick has concluded that there was collusion between members of the Garda Síochána and the Provisional IRA in the murder of Chief Superintendent Harry Breen and Superintendent Bob Buchanan. Worryingly, while Judge Smithwick has drawn this conclusion, the report further concludes that there was a general culture that existed and still exists within the Garda, where loyalty to the force is more highly regarded than honesty.

The long and winding process of the tribunal has been traumatic for the families of the two senior RUC officers who were murdered by the Provisional IRA in March 1989. They have courageously relived the horrors of that dreadful day in the hope that they would finally establish whether Garda colleagues, who the RUC officers thought could be trusted, had a direct hand in sending them to their deaths.

The IRA and their cheerleaders like to style themselves as an army, yet it is worth recording again the circumstances of the deaths of these two brave men. Bob Buchanan attempted to drive the car they were travelling in out of danger but the vehicle got stuck in a ditch. He was shot in the driver's seat. Mr Breen got out of the car, put his hands in the air and attempted to surrender. He was shot to death. Soldiers in an army don't shoot people trying to surrender. It is also worthy of note that the IRA failed to co-operate fully with the tribunal. They withheld vital information and lied about the collusion. So much for calls by Gerry Adams and other republicans for a truth process.

The efforts made by senior government ministers in Leinster House to hurry along the truth recovery process by attempting to impose arbitrary deadlines on the work of the tribunal did nothing to make the ordeal of the families any easier to bear. Judge Smithwick was correct in his assertion that such behaviour was "wholly inappropriate". To date, we have not received an adequate explanation as to why such a course of action was undertaken in the first place, but I am glad the Irish Government relented and allowed Judge Smithwick to complete his important work. Their apology to the families is also to be welcomed.

Police accountability
Levels of police accountability and scrutiny throughout these islands have increased. The PSNI, for example, is one of the most heavily scrutinised police forces in the world. This is why the conclusion that a culture of loyalty being more valued than honesty still exists within the Garda should worry all citizens in the Republic. In the context of the murder of innocent people, all who are interested in finding out the truth should be concerned to see this culture examined and its out-workings explored fully. We need to know if there was further such collusion and why the leadership of the Garda Síochána failed to address it when they had evidence presented to them by their own officers. Never before has Juvenal's old maxim, Quis custodiet ipsos custodes? – who guards the guards? – seemed more appropriate.

It has been argued that the government headed by Jack Lynch assisted in the expansion of the Provisional IRA when it was in its infancy. There is now, for example, little doubt that Capt James Kelly, the Irish intelligence officer, was acting on the orders of the then Irish government in seeking to acquire and import guns into the Republic for PIRA use. We also now know that Capt Kelly and other senior members of the Irish government met with senior figures in the IRA as early as October 1969. We know that Charles Haughey met with Cathal Goulding, the IRA chief of staff. These documented facts point to a sometimes sympathetic environment for the IRA. They should be examined as part of any process agreed to deal with the legacy of our troubled past.

One of the reasons why Margaret Thatcher signed up to the Anglo Irish Agreement was to tighten security along the Border. Judge Smithwick has since confirmed that political expediency meant it was decided to dismiss the connection between the IRA and the Garda in the murders of these two senior RUC officers. Authorities on both sides of the Border may have had a vested interest in denying the collusion of Garda officers with the IRA. For the then UK government it would have meant conceding that the agreement had failed in its stated aim, while for the Dublin government it would have meant admitting collusion with a criminal terrorist organisation. The consequence of this expediency was to deny the Breen and Buchanan families the truth for a quarter of a century.

Truth and justice
Judge Smithwick concluded that political expediency should not come before the need to provide truth and justice to the victims of terrorism. This is a principle that all parties to the current Haass talks would do well to uphold.

I welcome the fact that senior Ministers in the Republic of Ireland, as well as the Garda Commissioner have been clear in accepting the findings of Judge Smithwick and expressed their abhorrence at the circumstances that led to the murder of these two RUC officers. As for the dismissive comments of Gerry Adams, they stand as further testimony to the hypocrisy and callousness of the republican movement towards its victims. I have no doubt that the vast majority of officers in the Garda Síochána and the people of the Republic will continue to shun those who supported or those who seek to make excuses for the actions of an illegal organisation that engaged in cold-blooded murder.

We must ensure that this dark chapter in our shared history is never repeated.

Jeffrey Donaldson is Democratic Unionist MP for Lagan Valley and party spokesman on Victims Issues