Laura Klein Croft is a retired US Army Lieutenant Colonel. Tom Tugendhat is the Conservative MP for Tonbridge and Malling. In 2013 they co-wrote The Fog of Law, a paper from Policy Exchange on the legal erosion of British fighting power.

Yesterday the Supreme Court handed down a set of major rulings in cases involving claims against UK military and government officials for actions taken abroad in pursuit of national security and British foreign policy.

The significance of these judgements, and their relevance to central policy questions, confirms the importance of judicial power in our constitution.

While the litigation involves a mix of old and new legal grounds – the law of tort and European human rights law – the extent to which legal proceedings are now used as a way to challenge military action is remarkable. The contrast between, say, the legal aftermath of the Iraq War and the Falklands War is striking.

Two of the judgements are important victories for the Government in limiting legal frustration of military action abroad.

One of the judgements demonstrates a new, welcome sensitivity to the demands and difficulties of British military operations in what international legal jargon calls “Non-International Armed Conflicts” or NIACs (in this case, the armed conflict between the UK and Taliban fighters in Afghanistan). Another judgement restores a legal doctrine, that of “Crown act of state”, which is likely to limit the misuse of tort law to challenge or frustrate military operations abroad.

In a third judgment, the Government was defeated, with the Supreme Court allowing a number of claims against intelligence officers and others to proceed to trial.

Serdar Mohammed v Ministry of Defence was brought against the Ministry of Defence by a Taliban commander and bomb maker who claimed that his 2010 detention by British forces in Afghanistan was unlawful and in breach of the UK’s obligations under the European Convention on Human Rights (ECHR). The Government faced two legal challenges, one in the private law of tort (claiming damages for wrongful detention), and the other under the Human Rights Act 1998.

The Supreme Court’s rulings yesterday mean that the first has failed comprehensively and the second has largely failed (part of Mr Mohammed’s claim, relating to Article 5(4) of the ECHR, will now return to trial).

The Court held that the detention of Mr Mohammed by British forces was legal. This was because the United Nations Security Council Resolution (UNSCR 1386, adopted under Chapter VII of the UN Charter), under which the NATO coalition operated in Afghanistan, authorised the military of member states participating in conflict in Afghanistan “all necessary measures”, which the Court held includes the detention of combatants for imperative reasons of security.

The Court found against Mr Mohammed’s claim for damages on the grounds that the doctrine of Crown act of state bars claims in tort against the Government for its acts abroad. This longstanding common law doctrine, which was last applied by the courts in the 19th Century, but which has counterparts in many foreign legal systems, traditionally applies to the making and conduct of war, treaty making, and other core matters of foreign policy.

The judgement is an important victory for the Government in relation to litigation arising out of operations in Iraq and Afghanistan, and it will reduce the legal risk to the Armed Forces when detaining enemy combatants during overseas operations.

As the Ministry of Defence has remarked: “It is vital that our troops have the ability to detain enemy forces when they are engaged in conflict, and today’s judgement is a significant step in clearing up the legal fog that has surrounded the issue.”

The Court’s interpretation of Article 5 of the ECHR in Serdar Mohammed is commendably consistent with the need to ensure the effectiveness of military operations. However, it remains the case that regulating armed conflict by way of International Human Rights Law (IHRL), rather than International Humanitarian Law (including the Geneva Conventions and so on), is deeply problematic.

As explained in two successive Policy Exchange reports, the former is suited for domestic peacetime conditions and is not easily transferable to situations of conflict, where the lethal threat to forces is fast moving and continuous.

Earlier decisions of the European Court of Human Rights (ECHR) have improperly extended its mandate to military operations abroad, creating much uncertainty and bringing the Supreme Court to this juncture.

Indeed, the ECHR may yet hold that the Supreme Court yesterday misapplied or misunderstood the Convention, and the judgement has not resolved the problematic application of IHRL to the battlefield. The question of the proper reach of the ECHR continues to loom large.

Moreover, despite the Supreme Court’s welcome and sensible ruling on the authority to detain in this particular case, it is worth noting that several of the UK’s operations abroad, not least those ongoing in Syria, are not being conducted pursuant to a Chapter VII resolution of the UN Security Council which authorises “all necessary measures”.

Given the fact that Russia and China have vetoed draft resolutions which would have authorised the use of force in Syria, this is likely to be the case in the future. It may well be prudent for Parliament to legislate to authorise detentions in conflicts abroad.

It also remains unclear, after yesterday’s rulings, when or whether the Crown act of state doctrine applied in Serdar Mohammed’s case might similarly protect intelligence officers and other government officials carrying out UK foreign policy abroad.

In the Belhaj case, the Court ruled that neither the foreign act of state doctrine, which provides that British courts will not adjudicate upon certain acts of other states, nor the doctrine of state immunity ruled out a claim against intelligence officers and others for alleged involvement in ill-treatment of the claimants by other states.

The ruling in Belhaj, which has been much more highly publicized than Serdar Mohammed, might suggest that intelligence officers are more vulnerable to tort claims for actions carried out in pursuit of their duties than their uniformed military colleagues.

The Belhaj judgment will require further consideration to ensure that national security operations, including liaison with foreign security agencies, can proceed in a workable way. Like military personnel, intelligence officers are rightly subject to the law, but the law should enable – not frustrate – effective action to defend the realm.

It remains to be seen whether the Court’s approach in Belhaj strikes the right balance. It may be that rather than letting a new regime develop by way of case law, Parliament should legislate to specify further the legal framework within which intelligence officers operate.

There is little question that Britain’s utility as a military ally to the United States and other Western powers has been diminished by the crisis in recruitment, retention, and overall morale in the UK armed forces, and that one of the key ingredients of this crisis has been the “fog of law” – to use the phrase coined in Policy Exchange’s first report on point – and the legal abuse of British military personnel.

Uncertainty about the legal standards governing detention – and the related risk of liability for detaining enemy combatants – has been an important part of this phenomenon, as our two reports argue, and the greater certainty that yesterday’s rulings provide is valuable. More generally, the rulings go some way to confirming that this trend can be halted.

However, while these decisions of the Supreme Court in relation to military action are welcome and important, they are in a sense limited victories, which do not wholly roll back the wider trend towards the juridification of war – and indeed of national security more generally.

Reversing that trend will require further action, including ending the military’s liability for negligence and preventing the application of the ECHR to military action abroad in the first place, as well as its adjudication in British courts.

This could include derogation from European human rights law by way of Article 15 of the ECHR, and amendment to the scope of the Human Rights Act to make clear that it does not apply extra-territorially, such that ECHR challenges to the UK’s military operations abroad could not be brought before the UK courts.

The Supreme Court took some significant steps yesterday to limit judicial interference with military action. However, it remains to be seen whether the newly re-asserted and redefined Crown act of state doctrine is capable of applying to intelligence operations. Given the remaining uncertainties, it is now time for Government and Parliament to introduce more thorough-going limitations.