Let us assume that all schools in future will have a police presence.
Concern about the carrying of knives and other weapons has led to the suggestion that airport-style security devices should be installed in schools. Add to this the possibility of checks for drugs by sniffer dogs, and the installation of cameras to monitor not only what happens after school hours but also the movement and actions of pupils during the school day.
The intended outcome of these various measures would be to reassure parents that everything was being done to make schools safer places. But what about the unintended outcomes? First, there would be a major impact on the ethos and climate of schools. From the pupils' perspective, they would become much more like custodial institutions than they are at present. The regime of surveillance would lead to resentment and might even provoke incidents that would otherwise not have occurred.
Furthermore, the time and effort devoted to maintaining order would carry the implicit message that learning was of secondary importance to discipline. This runs counter to research evidence which suggests that a positive school ethos depends on putting learning at the heart of school life - exemplified by good lesson planning, high teacher expectations, constructive feedback and imaginative pedagogy.
Second, the atmosphere of relentless policing would serve to undermine those aspects of school life that are designed to provide pastoral care and encourage personal and social development. Teachers who deal with vulnerable youngsters know only too well that establishing a good relationship depends on building trust and confidence, and that heavy-handed interventions can be counter-productive.
Third, the reaction of some parents might be hostile. In the aftermath of an incident which leads to the death of a pupil, they might well call for heightened security. But they might also object to practices which they regarded as an infringement of their children's rights, implying that they were potential criminals.
Already a small number of parents choose to educate their children at home for a variety of reasons, sometimes to do with concerns about bullying and intimidation. That number might increase if the system itself was seen to be enforcing intimidatory measures, albeit ones designed to enhance safety.
Fourth, what of the response of teachers? There could be an effect on recruitment as they might be put off by the prospect of operating in an environment which they regarded as oppressive. It is not hard to imagine tensions between teachers and support staff whose job it is to implement the various checks intended to prevent unacceptable behaviour.
One future scenario of schooling produced by the Organisation for Economic Co-operation and Development is called the "Doomsday Scenario" and assumes dysfunctional schools, loss of parental trust, teacher flight and political failure.
Although we are well short of that situation at present, it is worth keeping it in mind as a cautionary counterweight to those who call for ever-tighter measures of control. Schooling has always had to tread a careful and difficult path between freedom and authority. There are no easy solutions.
Walter Humes is research professor in education at Paisley University.