The evidence is in and the verdict is clear: if schools embrace democratic values and headteachers are prepared to canvass the views of their staff and promote leadership at all levels, the education of their pupils gets better.
This is the view of the increasingly influential team behind the Programme for International Student Assessment (Pisa) rankings. They argue that schools must be places of learning not only for pupils but also for teachers, and that the most effective school leaders learn from their teachers and vice versa.
Reinforced by last month's Teaching and Learning International Survey, the 2012 Pisa results show that the countries that promote collaboration between teachers and school leaders rank more highly in international league tables. Andreas Schleicher, the coordinator of Pisa, recently wrote: "Teachers are the key resource in education; and how they are developed and supported throughout their careers necessarily has a strong impact on the performance of students and schools - particularly those with greatest need."
So the message is clear: the quality of a nation's education system cannot outstrip the quality of its teachers. Teachers need to be listened to and invested in. Schleicher goes on to argue: "Given the complexity of teaching and learning, high-quality professional development is necessary to ensure that all teachers are able to meet the needs of diverse student populations, effectively use data to guide reform, engage parents and become active agents of their own professional growth."
Schleicher's inspiring vision is for teachers to play an active role in schools that value their input in decisions about professional issues such as the curriculum, teaching and assessment, school ethos and much more.
So far, so easy. My view, however - backed by surveys carried out by my union and others - is that democratic leadership is too often the exception rather than the rule. Driven by quantitative performance measures and the pressures of accountability, school leaders become more isolated and distant from their colleagues, and more directive as leaders and managers. And in too many schools, compliance is valued and fostered much more than creativity.
Everyone loses in this scenario: autocratic and isolated school leaders; frustrated teachers, who have much to offer but feel their expertise and experience is not properly used; and pupils, whose standard of education suffers because teachers are not allowed to be innovative.
Strong evidence from England supports this view. In addition, there is convincing evidence to show that instead of being encouraged to collaborate with colleagues and to think about teaching, pedagogy and their subjects, teachers are being weighed down by a bureaucratic nightmare.
A primary school teacher will work an average of 59 hours a week and a secondary teacher 56 hours. Teachers are not shirkers. They don't mind hard work. They do, however, mind unproductive work that does nothing to improve their teaching or advance pupils' learning. Yet the majority of this excessive workload, which is driving out teachers at all stages of their careers, is not focused on improving teaching or learning but on recording what teachers have done or are planning to do. It's as though nothing is done - no differentiation, no Assessment for Learning, no group work - unless it is written down.
Why do school leaders make these demands of their staff? I believe that they enforce these unproductive ways of working because of the immense pressure they are themselves under. In England, school leaders' jobs are as secure as the inspection grade awarded by Ofsted. As a result, leaders too often resort to dictatorial ways of working: telling teachers what to do and insisting on ridiculously bureaucratic lesson planning and assessment frameworks.
And just when we need the best leaders in highly challenging and highly deprived schools, the inspectorate's sword of Damocles hangs over any senior leader foolish enough to think they will be given sufficient time to undertake the tricky business of turning around a school with seriously entrenched problems. Ofsted has ensured that leaders moving to these schools significantly raise their risk of committing career suicide.
Labouring under intense pressure from a crude, inefficient accountability regime, which suffers from systemic and endemic quality-control problems (an inspection grade rests on the quality of the inspectors who arrive at the school gate), many school leaders play it safe. They want a record of everything so that when the inspector calls, they can demonstrate that they know exactly what is going on in their school.
This means that teachers are drowning in data, being buried under record-keeping and being laid low by lesson plans that can run to five pages or more.
If countries are serious about valuing their most precious educational resource - their teachers - they need to do much more to demonstrate that they appreciate staff and respect their professional expertise. They need to invest in teachers through high-quality, readily available CPD. They need to fully adopt the idea of democratic school leadership.
But this will never happen if headteachers continue to bend under the pressure of inspectors and governments that inspire fear and compliance, and then pass their heavy burden on to teachers.
Dr Mary Bousted is general secretary of the ATL teaching union