Moi Ali, the country's first Judicial Complaints Reviewer (JCR), will not seek a second term because she believes her post is "tokenism".
The JCR post was created by the Scottish Government to introduce an element of independence in the system of self-regulation for scrutinising judges.
However, Ali's role is restricted to looking at whether the Judicial Office for Scotland (JOS) - the in-house body led by the Lord President - has dealt with complaints correctly.
She cannot investigate complaints against judges herself and is unable to make recommendations.
Ali, who took office in 2011, also works on a tiny budget of around £2000, whereas a beefed-up Ombudsman south of the border has nearly £500,000.
In an interview with the Sunday Herald last year, Ali said she had found the job "enormously frustrating and difficult", adding: "Fundamentally the problem is the legislation ... it's judges judging judges' conduct.
"I'm presented as the independent element, but without the powers I can't be independent."
She added: "Really, it's difficult to make an impact within the constraints that I'm in at the moment. It's a bit like being in a straitjacket."
Ali also claimed Scotland was lagging behind England in holding judges to account, claiming: "Citizens here have a lot less protection than they do in England and Wales."
The JCR has also encountered difficulties with the JOS and claimed the post amounted to "window dressing".
The Sunday Herald has learned that Ali, whose term ends in August, will not seek an extended period in office, where she could have served five years. She wrote to Justice Secretary Kenny MacAskill before Christmas to inform him of her decision. MacAskill will have to find a new JCR, an appointment that must be made "with the consent" of the Lord President.
In her latest annual report, she found 20 breaches of the rules by the JOS last year.
Ali said: "I believe that I've been able to make a difference, albeit in a small way - which is not only personally satisfying, but important for the people who use my service. Ultimately, that's what it's all about.
"I feel that I have achieved all that I can within the constraints of legislation that has created a JCR role that has independence without the power to change anything.
"I can freely comment, criticise, persuade, suggest, speak out - but I have no power to make things different and better.
"Without the ability to implement change, the role feels tokenistic and I've never been one to go along with tokenism."
Graeme Pearson, Scottish Labour's justice spokesman and a former top police officer, said: "Moi Ali accepted an important responsibility and was keen to do the job.
"She should have been supported and encouraged - instead her role developed as an unwitting sop for this SNP Government at a time our justice system requires genuine openness and accountability. She and the Scottish public deserved better."
Liberal Democrat MSP Alison McInnes said: "The Justice Secretary asked Ms Ali to do a job and then point-blank refused to give her the support and resources she needed to deliver. This is simply not good enough.
"Moi Ali's frustration over the lack of support she has received from ministers is wholly understandable. Her decision to stand down is an indictment of the lacklustre approach to transparency that the Justice Secretary has taken."
A Scottish Government spokeswoman said: "We do not comment on personnel issues. We thank Ms Ali for the work she has done in her post to date."