A legal watchdog has called for a change in the law after it emerged the public cannot make any complaint about Scotland's most senior judge.

Moi Ali, the Judicial Complaints Reviewer (JCR), has discovered that every member of the Scottish judiciary except the Lord President - currently Lord Gill - can be held accountable for their conduct.

She said complaints had been made to her about Lord Gill that could not be considered, which was an outcome that left the individuals involved feeling "outraged".

Members of the public who have a grievance against a judge or sheriff can contact the Judicial Office for Scotland (JOFS), headed by the Lord President.

If someone is unhappy about the way their complaint has been handled, Ali can also launch her own investigation. However, in a letter to Justice Secretary Kenny MacAskill, she said the complaints process creates a two-tier system: a set of rules for ordinary judges but nothing for Lord Gill.

She stated that two people had approached her with complaints about Lord Gill's conduct, but no investigation could be launched.

In the letter, released by the Scottish Government, she wrote: "Normally I would refer any complaints to the Judicial Office (as I do not handle complaints; I merely review their handling). However, on this occasion there seemed little point in referring complaints that I knew could not be considered under the rules."

She added: "They were outraged that they had no redress, felt disempowered and denied justice. Their view was that the head of the judiciary should be subject to the same rules as those beneath him, and that the public should not be denied access to the complaints process just because their judge happened to be the most senior one."

Ali said she had "considerable sympathy" for the complainants, adding: "[I] believe that a fair, independent and proportionate procedure for investigating complaints about the Lord President would enhance public trust and confidence in the judiciary among the public, and would be in the interests of natural justice."

The watchdog said she had raised the matter with Lord Gill and had taken advice from senior counsel, according to which the only complaint that can be made about Lord Gill concerns his "fitness for office" - a nuclear button option.

As a stop-gap solution, Ali asked the Lord President if it could be made clear that conduct complaints cannot be made about him. She also requested clarification of the process for making a "fitness for office" complaint about the judge.

However, she told MacAskill: "The above are interim measures only that do not address the fundamental issue - that there is no provision for the public to make complaints about the Lord President's conduct, including when he is sitting as a judge. I would be grateful if you could give this matter consideration."

It is understood that every other public servant - from council workers to the First Minister - is subject to a complaints process. The issue appears to be another example of the law shielding judges. When Holyrood launched an inquiry into whether they should be required to publish a register of interests, Lord Gill refused to give testimony, as the legislation creating the Parliament states that judges cannot be compelled to give evidence. Lord Gill said the exemption helped "protect the independence of the judiciary". Judicial officers are also not required to declare gifts.

Ali, who works on a shoestring budget of about £2000, was appointed as JCR for a three-year term in 2011. In her first annual report she was candid about tensions with the JOFS regarding her remit. Regarding the conclusion of her investigations, she said: "My view was that I could share wider recommendations stemming from a review with the complainer, but the Judicial Office took the view that this was a private matter between me and the Lord President and that I was limited to telling complainers only whether or not the rules had been followed."

Ali also stated that the JOFS was not providing her with all the documents necessary for her cases. "They gave me all correspondence between themselves and the complainer," she said, "but I was not being sent copies of correspondence between the Judicial Office and the disciplinary judge, nominated judge and Lord President relating to the complaint. I believe that in order to conduct a review, and to make wider recommendations on complaints handling, I need to see files in their entirety. Without this, it is difficult to satisfy myself, let alone complainers, as to the fairness of the process."

Graeme Pearson, Scottish Labour's shadow justice spokesperson, said: "No-one should be beyond complaint in a democratic country - even the Lord President. Mr MacAskill must address this situation and fix it."

Liberal Democrat MSP Alison McInnes said: "The fact that the person responsible for overseeing complaints has real concerns over the current rules should raise a big red flag in Kenny MacAskill's office.

"It seems strange that the Lord President should have a degree of immunity from public scrutiny and there is a strong case for ministers to look at these rules again."

Ali said yesterday: "For the public to have faith in the complaints system, it is vital that it covers all members of the judiciary, from the most senior to the most junior. For that reason, I would like to see an impartial, fair and proportionate, well-publicised system in place to consider conduct complaints about the Lord President."

A Scottish Government spokesperson said: "The Lord President's office is unique as the head of the Scottish judiciary, whose independence is enshrined in law through the Judiciary and Courts (Scotland) Act 2008. Because [the Lord President] is the head role, the Act takes a different approach to oversight in the Lord President's case - and would require the constitution of a tribunal. This recognises a balance has to be struck in terms of how oversight of the Lord President's role should ultimately be achieved in a way which fiercely protects its independence."