AT rush hour in Belfast city centre on Tuesday evening, only yards from the building where the International Body on Decommissioning was in session, plain clothes RUC men opened fire as a vehicle escaped from them.
No clear reason for the shooting has been made available, other than that the officers were on anti crime duty and the car was believed to have been stolen. The RUC press office has been unable unwilling or unauthorised to specify whether the police fired at the occupants, at the vehicle generally, or into the air.
The incident - which is by no means unprecedented in the North - raises long standing unresolved issues concerning police accountability and the use of lethal force. It also lends weight to the Sinn Fein contention that weapons held by the security forces should come into the whole decommissioning/demilitarisation debate.
It appears that nobody was injured in Tuesday's shooting. If somebody - either a passerby or an occupant of the car - had been killed or wounded, the officer or officers who discharged their weapons might (but only might) have been called to account in court for their actions. That would depend on an investigation by the RUC, and ultimately on a decision by the DPP. A civil case might also be brought.
The ground rule on the use of force (by soldiers and police alike) in pursuit of an arrest, the prevention of crime and disorder, or self defence, is Section 3(1) of the Criminal Law Act (Northern Ireland) 1967. It demands that the force applied to prevent crime or effect an arrest be "reasonable in the circumstances".
In fact this is a provision of extraordinary latitude and flexibility, as has been demonstrated repeatedly in the North. The application of this section and associated issues has been at the centre of controversy in most of the several hundred killings by the security forces during the 25 years of the Troubles.
It has been pointed out that Article 2 of the European Convention on Human Rights demands that lethal force, if used, be "absolutely necessary" - and that "absolute" is a more rigid standard than "reasonable".
Strong academic and judicial opinion supports the view that Section 3 demands not only that a reasonable person would think that the force used was justified to avert the potential evil, but also that force was unavoidable to achieve the objective. Certainly, the legal provision is extraordinarily vague in relation to such a vital matter of life or death.
There are, of course, internal police guidelines on the use of firearms, but the RUC says these are confidential. In relation to soldiers the issue is more open because of the Yellow Card setting out "Instructions for opening fire in Northern Ireland".
This card is said to have been revised recently. It is not generally available, but the terms it sets out have emerged in many court hearings in the North.
A section read out in one murder case against a soldier said: "You may only open fire against a person if he is committing or about to commit an act likely to endanger life and there is no other way to prevent the danger."
It also gave some examples of acts where life could be endangered, "dependent always upon the circumstances". These included: "Firing or being about to fire a weapon.
Planting, detonating or throwing an explosive device. Deliberately driving a vehicle at a person and there is no other way of stopping him."
The Yellow Card also stated: "If you have to open fire you should: fire only aimed shots; fire no more rounds than are necessary; take all reasonable precautions not to injure anyone other than your target."
While the courts have repeatedly acknowledged that the Yellow Card has no inherent legal force, they have often had regard to its provisions in considering whether the force used by a soldier or soldiers was reasonable in the circumstances.
The Lord Chief Justice, Sir Brian Hutton, has stated that ... whilst firing in accordance with the instructions in the Yellow Card may in many cases be found by a court to be reasonable force used in self defence, or in the defence of others, or in the prevention of crime, it does not follow in every case that because the firing can be brought within the literal terms of the Yellow Card the firing must be held by a court to constitute reasonable force and to be lawful."
In the case of Private Lee Clegg, the defendant's conviction for murder was upheld by the Court of Appeal because the court judged that he had fired a high velocity shot to kill or severely wound the driver of a car which had failed to stop for an army patrol and had knocked a soldier off balance.
The crucial factor was that the bullet which struck the victim, Karen Reilly, was judged to have been fired after the car had passed the patrol and was moving away - therefore no longer directly endangering the soldiers.
The courts have repeatedly shown that they take a very serious view of soldiers opening fire to stop cars or effect an arrest. But although police officers are subject to the same legal restraints, they have, in the main, escaped a detailed judicial examination of their criteria for using their guns.