For the parent of a child facing barriers to learning at school, a co-ordinated support plan (CSP) is supposed to achieve a number of things.

Children who need any help with a health problem, a disability or a behavioural condition may need additional services beyond those the school can provide.

If an assessment is requested, local authorities are required to consider whether extra help is needed to ensure the child has the best education possible.

If it is, they need to decide who should provide it - their own education or social work department, for example, or a local health board or college.

The CSP specifies which school the child will attend, what outside help is needed from other agencies and who will ensure that help is given.

The plan is created in consultation with the child's parents and once agreement has been reached on the child's needs for the next year, it is signed by the local authority and copies are given to the family.

But what is the point of all this? Until a recent tribunal, the parents of Thomas Lloyd thought their nine-year-old autistic son had been promised speech therapy by the local authority. Instead, the ruling was that although the pledge was in his CSP, the council was within its rights not to actually come up with any speech therapy.

The family's lawyer says this means CSPs are not worth the paper they are written on.

It would certainly seem that they are not always the guarantee families thought.

Charities thought it too. "The local authority must make sure that the child or young person receives the support outlined in their plan," Autism Scotland advises parents.

It is possible that the needs of a child can change. Speech problems, for instance, can resolve themselves in the company of other children, or as a child develops.

But Glasgow City Council would have been on firmer ground if it had provided the service first and later reviewed the need for it.

One wider issue the case raises is the frequency with which such disputes are having to be resolved in the courts. In June we reported on the case of wheelchair user Thomas Pettigrew, who won a case against his local authority after being excluded from guitar lessons.

The council - South Lanarkshire - was deemed not to have met its duty to make "reasonable adjustments" to avoid disadvantaging a disabled pupil.

The time and cost involved in such cases are considerable. There also has to be some sympathy for councils facing severe cash limitations, which are nevertheless subject to wide-ranging and uncosted duties of provision.

However, the intention of a CSP was to give parents a recognition of their child's needs, and an apparent guarantee that they can be met. This ruling throws it into doubt for thousands of parents.

The Scottish Government says the situation is clear and local authorities know their duties under the law.

But this ruling leaves the situation looking far from clear. If councils do not feel it necessary to follow through on the content of a plan, it is hard to understand what purpose they truly serve.