The rule 'he who pays the piper picks the tune' does not apply directly to the NHS but legal consultation duties come some way close. The NHS is a public service so all the money it spends is coughed up by the public in taxes. Consultation duties are about giving the public a say in how their money is spent. But it is a say, not a veto.

'What,' I hear you ask, 'consult the public? What do they know?' Some health managers - and many MPs - feel the public have unrealistic expectations of the NHS, demanding a near perfect health service, always local to them, with 100 per cent positive outcomes and at virtually no cost. They also want nurses to be paid more - although not doctors, but that's another story.

Under section 11 of the Health and Social Care Act 2001, the part subtitled 'why we must never have another Kidderminster' states that the public have a right to be consulted on 'the planning of the provision of NHS services'. They also have a right to be consulted on 'the development and consideration of proposals for changes in the way services are provided and decisions to be made by NHS bodies affecting the operation of those services'. Is that clear? Well not quite. In a masterpiece of judicial understatement Mr. Justice Collins said the 'the language is somewhat imprecise'.

Section 11 was supplemented by Department of Health guidance, Strengthening Accountability Involving Patients and the Public. This document appears to have been written by some naive consultation enthusiasm junkies who had wholly unreal aspirations about what consultation could achieve.

It say: 'The new duty will strengthen accountability to patients and the public and make sure there is transparency and openness in decision making procedure. We must develop and adapt health services around the needs of patients and the public which will build trust and confidence between local communities and the NHS.'

Try telling that to a sceptical public where an opposition politician is trying to jump on a bandwagon of some perfectly sensible change in local NHS services to get elected to the local council, parliament or wherever.

Arguably every decision an NHS body makes affects local health services - that is what NHS bodies do. So does a primary care trust have to go through a 13 week 'Cabinet Office' style consultation exercise before staff member is appointed or the most minor change is made to opening hours or local services? The answer is not quite but nearly. The courts have interpreted the section to mean that NHS has a duty to maintain a dialogue with the public, and consult specifically on significant changes or anything which is locally contentious.

In North Eastern Derbyshire v. Smith the court struck down the PCT's decision to appoint United Health Europe to provide GP services in two villages - including the village in which the claimant, Mrs. Smith, lived - without consulting the public in advance. Involving the near moribund patient's forum with a nod to the local council was not enough. Local campaigners were entitled to their say before the plans went ahead even though it was only changing one GP for another and so arguably altering nothing for the local population.

The issue came up again in a case involving Trafford Healthcare trust, which temporarily closed some inpatient wards. The 'it was only a temporary closure' argument did not wash. The court picked up the words of Strengthening Accountability, saying: 'What is important is that involvement and consultation is adequate both in terms of time and content and appropriate to scale of the issue being considered.' Here, the Judge held that 'there appears to have been no or virtually no consultation with the public in its wider sense and certainly not with the [public and patient involvement forum]'.

Failing to consult the public as required by section 11 is unlawful and the pressure from the strategic health authority to deliver savings yesterday is no defence. Whilst a full 13 week style consultation may not be required, making contentious permanent or even temporary changes to NHS services without alerting the public and giving the chance to have their say is a risky business.

Astute local campaigners may commence judicial review proceedings which could lead to the court stopping the service changes until consultation has happened, and the PCT ending up with a huge legal costs bill. Better to be open and consult in advance - you might even build a consensus for change.

David Lock is head of healthcare at Mills & Reeve