The Freedom of Information (Scotland) Act, or FoI, was not only one of the world's strongest laws on access to information when it was passed in 2002, it has also proved its worth in promoting a more open culture across officialdom.

On everything from hospital-acquired infections to the closure of schools, health and safety to MSPs' expenses, the legislation has given the public the right to know how government, local councils and other public bodies act on their behalf.

Which is why, if freedom of information legislation is to remain effective, it has to be constantly reviewed, strongly protected and any threat to it tackled swiftly. In the 12 years since the act was passed, the information commissioner, who is responsible for enforcing the law, has occasionally had to warn against vested interests protecting their secrecy in spite of the legislation. It is a reminder that freedom of information is a valued and important concept, but a fragile one too.

The commissioner, Rosemary Agnew, yesterday repeated some of these concerns when she outlined the extent of failures by some public bodies to respond to FoI requests. In all, 34 Scottish public authorities were the subject of appeals about failure to respond last year and they included a number of local councils, the Scottish Prison Service, Transport Scotland and the Scottish Government itself.

It is important to note that the numbers involved are relatively small and that most public bodies respond well to FoI requests most of the time. But even so, almost one quarter of all the valid appeals the information commissioner receives are about public authorities' failure to respond to requests on time, or at all, even though they are legally required to provide a full response within 20 working days.

The commissioner is only doing her job in drawing attention to this and also warning that, if left unchecked, failures to respond to requests could undermine the high regard in which Scotland's FoI regime is held. However, she also points out that there appears to be a correlation between failure to respond and specific requesters - in other words, some public bodies may be failing to respond because they are reluctant to engage or encourage certain vexatious or obsessive requesters.

The risk of such vexatious requests is always likely to exist in a system that is so open to the public, but that cannot allow public authorities to avoid their obligation to respond to requests on time. As Ms Agnew says, when authorities do not respond, they create unnecessary stress for the individual and effectively deny his or her legal rights.

The hope now is that naming the authorities that have failed to respond, as Ms Agnew has done, will help to remind them of their responsibilities and the Scottish Parliament of its obligation to protect and strengthen the legislation if necessary.

The FoI regime is a valued part of Scottish public life, but public confidence in it will be damaged if some public bodies continue to resist requests.