The High Court review into the government's decision not to hold an independent inquiry into the alleged killing of Iraqis by British troops could spell changes for the UK military.
The stakes could hardly be higher, both for the British military and the government.
And if this court action ultimately ends in a judgment against the Ministry of Defence, it may well have implications for peacekeeping operations in many parts of the globe.
British forces are involved in many operations worldwide
But a number of legal thresholds have to be crossed for that to happen.
The crux of the case is whether the Human Rights Act applies to the behaviour of British troops occupying southern Iraq and, if so, whether they have violated the rights of Iraqi civilians.
If the answers to those questions are yes, the short-term consequence would be an obligation on the government to set up an independent inquiry to establish what happened and who was responsible.
The Bloody Sunday inquiry is one possible model though lawyers would resist such a time-consuming and unwieldy tribunal.
It is likely that there would be a successful claim for monetary compensation.
Even if the applicants lose, the evidence of brutality will be reported around the world and do nothing to enhance the reputation of Britain's peacekeeping forces
And there could also be criminal prosecutions of any soldiers against whom there was sufficient evidence to place before a court.
But none of that will happen if the Ministry of Defence wins its argument that, although Britain occupies southern Iraq, it is not in de jure control. Therefore, the Human Rights Act does not apply.
The MoD will also point out that it has fulfilled its obligations under the Geneva Conventions by launching criminal investigations into at least five civilian deaths allegedly caused by British soldiers.
Human rights lawyers do not regard those investigations as meeting the requirement for independence as set out in the European Convention on Human Rights.
There is another possibility, admittedly an unlikely one, that would be even more embarrassing for Britain.
If the attorney general decided not to press criminal charges, an application could be made for war crimes indictments to be issued by the International Criminal Court.
International lawyer, Khawar Qureshi, said: "With the advent of the tribunals for Yugoslavia, Rwanda and Sierra Leone and now the ICC, the threat of criminal punishment is acquiring increasing importance in preventing possible breaches of the Geneva Conventions as well as punishing them. This should not be underestimated."
Whatever the outcome of this High Court hearing - and there is likely to be a reserved judgment at its end - this case seems destined to be heard eventually by the House of Lords.
Even if the applicants lose, any evidence of brutality will be reported around the world and do nothing to enhance the reputation of Britain's peacekeeping forces at a highly sensitive time.