“Betrayal of our soldiers – again!”. This was the Daily Mail’s front-page headline on the reported cabinet splits over plans to omit a statute of limitations for former soldiers from proposed legislation on dealing with the past in Northern Ireland. A statute of limitations, a mechanism that negates criminal liability for past crimes, is an amnesty by another name. The thing is, such an amnesty was never supposed to be in the legislation in the first place. The “betrayal” in question was an attempt by Conservative politicians and some allies in the DUP to shoehorn in something that none of the Northern Ireland parties or the Irish government ever signed up to in the first place.

The legislation in question is designed to give effect to the Stormont House Agreement (SHA) concluded between the two governments and the Northern Ireland political parties in 2014. It took years to negotiate and a further three years to prepare the enacting legislation. It will establish a police-led cold case review of conflict cases, a mechanism to allow families to seek truth about what happened to loved ones, a storytelling process and an institution tasked with assessing the “big picture” themes and patterns of the conflict. A statute of limitations was never mentioned. Indeed, no party argued for it during years of negotiations.

However, in 2017, the Conservative party-dominated defence select committee called for a statute of limitations for members of the armed forces who served in Northern Ireland. The DUP supported this move, even though they had never tried to argue for in the negotiations. The British government subsequently indicated a willingness to discuss the issue as part of the consultation on the legacy legislation.

So why is it off the table now? The reasons are both political and legal. A statute of limitations for security forces only is what the United Nations has termed a “self-amnesty … adopted by those responsible for human rights violations to shield themselves from accountability”. Such “self-amnesties” were introduced in former dictatorships in Argentina and Chile and by Robert Mugabe’s government in Zimbabwe. For the UK to join such a list would be quite extraordinary. Apart from the blow that the UK’s international reputation would suffer, an amnesty for British troops would provoke a furious reaction from Irish nationalists and undermine the broader consultation process.

The reasons why are straightforward. The state was directly responsible for approximately 360 deaths during the conflict. Many of these occurred in the early (and most violent) period that included Bloody Sunday. Between 1969 and 1974, 170 people were killed by the British army. No one was prosecuted. 63% of those killed were undisputedly unarmed, 12% (24 people) were armed and a further 14 were listed as being “possibly armed”. For many, an amnesty would retrospectively validate such a culture of impunity.

There are also direct legal consequences. Parliament could introduce an amnesty. However, as the defence committee acknowledged, such an amnesty could not deny victims their right to an investigation into what happened. Families would still receive reports (eg from the cold case review) about what happened, albeit without the chance of a prosecution. The defence committee did not conclude that an amnesty would apply to paramilitaries. However, in legal terms, a security forces-only amnesty would seriously undermine any conflict-related prosecution.

One argument, reiterated by Theresa May in the House of Commons, is that current processes are “unfair” to the armed forces. However, since 2011, seven republicans, three loyalists and three soldiers have been prosecuted for conflict-era offences. The prime minister also said that ‘“only those who served in law enforcement are being investigated … terrorists were not being investigated”. In fact, as Police Service of Northern Ireland figures show, the police are currently investigating 530 republican-linked killings, 271 loyalist-linked and 354 security force-linked deaths.

Another point raised in parliament was that the Good Friday agreement provisions on the early release of prisoners and the ensuing two-year maximum sentence rule for conflict-related offences did not apply to the security forces. In fact, there is nothing in the relevant legislation to suggest that soldiers or police would be ineligible. That legislation does not cover pre-1973 offences but this anomaly is easily rectified by shifting the eligibility date backwards.

Other parliamentarians argued that republican suspects benefited from the so-called “on-the-run” letters, an amnesty by another name. However, as was confirmed by Lady Justice Hallett in her review of this scheme, these letters simply confirmed to recipients that there were no current charges or evidence against them. Unlike an amnesty, they did not rule out a future prosecution if evidence emerged.

What would happen in cases of collusion where state agents were operating within loyalist and republican groupings? Would they qualify? The shallowness of these justifications for a “state actors only” amnesty would be exposed in court in any attempt to prosecute a paramilitary suspect, which defence lawyers would argue was discriminatory and unfair.

In short, the political consequences of the proposed statute of limitations would have been potentially dire – undermining years of painstaking negotiations. The legal effect would have been a de facto amnesty for all involved in past killings, which many victims would have found unconscionable. Wiser heads clearly prevailed within the government – and a good thing too. Now let’s consult on and implement what was actually negotiated.

• Kieran McEvoy is a professor of law and transitional justice at Queen’s University Belfast