Any elaborate legacy system is likely to turn against state forces unless London specifies probes into terrorism

The saga around the Northern Ireland Protocol and its predecessor, the backstop, in which the UK government position and stated aims have shifted back and forth, is almost five years old.

The saga around how to deal with the legacy of the Troubles, in which the UK government has had changing positions, is even longer.

In fairness to the government in London, this is an almost impossible topic on which to get agreement. But therein lies the problem. There was an assumption that legacy had to be agreed among political protagonists who ranged from supporters of the IRA to supporters of security forces to loyalists.

There was an agreement over legacy at Stormont House in 2014, but with time the consensus fell apart. And while the reasons for that unravelling are complex, one aspect of the way things panned out is telling — Sinn Féin became increasingly angry that Stormont House was not progressing. It was so confident that the proposed 2014 structures were good for republicans, it made their implementation a demand in talks.

Low ranking soldiers and being prosecuted for single, non pre-meditated killings and no IRA leaders — who orchestrated decades of murder and mayhem — seem to face any hint of the same, yet SF wanted to fast track a new system to deal with legacy. That hardly inspires confidence that Stormont House would have brought balance to a legacy process that has become so imbalanced against the security forces.

The UK government and many unionists at times seem slow to reach an increasingly obvious conclusion: that an elaborate legacy system will turn against the state unless specific inquiries are set up into terror, to be decided on balance of probabilities.

If terrorists face trial, few will be convicted.

Unless London has the stomach not merely for unilateral action to constrain the current legacy monster, but to make clear to terrorists and their political apologists that raking over the past will have consequences for them, and not just for veterans and ex RUC, the anti-state legacy juggernaut will motor on, sustaining an almost unending scandal.

• Other commentary:

• Lord Empey: The DUP have no-one to blame but themselves for disastrous election

• John Cushnahan: SF hypocrisy to attack DUP leader over MP seat while boycotting Westminster

• Peter Robinson May 11: Ignore those who are urging DUP to just go back into Stormont

• Editorial May 11: Liz Truss hints at action on NI Protocol but unionists are right to be wary

• Ruth Dudley Edwards May 10: The nationalist vote is nowhere near enough for border poll

• Editorial May 10: If Irish language gets pledge today so must an overhaul of protocol

• Ben Lowry May 9: The TUV vote surge should have been one of the main stories of the election

• Owen Polley May 9: Unionists have an issue with sectarian SF, not with nationalism

• Henry McDonald May 9: A few facts are in order amid breathless reportage about SF

• Emma Little Pengelly May 9: There has been no increase in the nationalist vote in 25 years

• Editorial May 9: It is clear that unionists need to have option of voting for a liberal party