The limelight was always going to be on Penny Mordaunt as defence secretary. A Brexiter accused by the last prime minister of lying to win, she is now touted as Theresa May’s emotionally intelligent successor. She did nothing to dispel such speculation with a speech on Wednesday, promising to protect soldiers from “lawfare” – a pejorative term coined to describe the use of a country’s legal system to undermine its defences. Ms Mordaunt said she would seek a presumption against prosecution for offences committed in conflict more than a decade ago – covering the wars in Iraq and Afghanistan; and seek a future opt-out of the European convention on human rights.

This is part of a familiar narrative about the hounding of British soldiers by what is claimed are money-grabbing lawyers launching ill-founded cases into alleged wartime abuse. It is true that one lawyer who acted for torture victims was found guilty of misconduct and struck off as a solicitor. But the work of the Iraq Historic Allegations Team also saw the Ministry of Defence paying out millions of pounds in compensation to victims of abuse in hundreds of cases. Modern armies have to comply with international humanitarian law and are rightly held to account if they don’t. This ought not impede conflict and post-conflict operations. It should ensure they are legal. Ending violations would end the litigation. There are about 150 cases outstanding; alleged victims and perpetrators ought to see justice.

There are a number of reasons why Ms Mordaunt’s consultation might not advance very far. First, Northern Ireland is excluded from the proposals. The prosecution of a former paratrooper for the murder of two people on Bloody Sunday in Derry in 1972 has angered the forces whom Ms Mordaunt, herself a naval reservist, is keen to champion. Second, an opt-out could not be sought for war crimes. Unless a genuine investigation was under way into such claims, they could be taken to the international criminal court. Third, there is no statute of limitations for the murder or torture of civilians.

Britain ought to be strengthening the international regime, not undermining it rhetorically. A report released on Thursday by Save the Children highlights how, lacking credible enforcement, the law has become a weak deterrent to criminality. The charity’s Stop the War on Children campaign highlights how they are far more likely than adults to be killed and maimed. We know who is responsible for possible Saudi-led coalition war crimes in Yemen. The same is true for what appear to be genocidal attacks on the Rohingya people by generals in Myanmar. Yet it is doubtful the that perpetrators will end up in court.

In Yemen the government can be credited with brokering a ceasefire. Yet it issues export licences to British companies who arm the perpetrators of possible war crimes. Riyadh sees commercial interest trump human rights. How does Britain stand up for the rule of law when it bends it the moment its own interests and soldiers are at stake? The problem is not a lack of legal protections, it is their corrosion by double standards and non-enforcement. Ms Mordaunt will not serve her country well by fostering a moral ambivalence about Britain’s human rights obligations. She’d do better by fortifying them.