Janet Garner was removed from the teaching register in November after a hearing that lasted three months, during which it emerged an entire top-set maths class had failed a test while under her guidance.
Figures released under Freedom of Information laws show the case has so far cost the General Teaching Council of Scotland nearly £175,000 – 30 times the typical amount – with the money coming from dues paid by teachers.
Mrs Garner, who taught at Alva and Alloa academies in Clackmannanshire between 2003 and 2007, was struck off in 2011, but that decision was overturned after the Court of Session ruled the General Teaching Council for Scotland (GTCS) had not properly proved the allegations.
She is now appealing to the court again after being removed from the teaching register last year following a second hearing.
The teacher faced a string of charges relating to rules on teacher competence, with witnesses claiming she made basic errors and repeatedly failed to control unruly classes.
In February 2004, test results for Mrs Garner’s S3 class at Alva Academy were so poor that the whole class of credit-level pupils failed overall, according to witnesses.
The teaching regulator said the cost of the case to date is £174,757, which includes legal fees, witness expenses and £20,000 spent on the Court of Session appeal.
Kenneth Muir, chief executive of GTCS, said: “This case illustrates that we will do everything to ensure high standards are maintained in the Scottish teaching profession. Members of the public and teachers should be reassured by this.
“The cost of this case is clearly a huge sum which was generated by the large number of hearing days involved and the associated legal costs.
“It is, of course, the right of an individual to defend their case and we will always stand by the principle of full and open hearings. We are very unhappy at the costs, which come directly from the annual fees paid by registered teachers, but we were left with no other option but to pursue this case.
“It is important to state that this case is an exception, with most cases completed within a maximum of two hearing days. We do not anticipate this outcome being repeated.
During evidence last year, Stuart Rycroft, a former deputy head at Alva Academy, said he had never had a teacher who had attracted so many complaints, and who needed as much assistance, as Mrs Garner.
He told the hearing in Edinburgh: “I hadn’t previously had any experience of so many parental complaints against a single member of staff.”
Mr Rycroft added: “My initial thought was that I would sit in the class and help to try to create a calmer atmosphere, but it was quite clear that the classroom had become a battleground.”
At a hearing in 2011, Mrs Garner was told by the GTCS she would be removed from the register as it had concluded that she “simply could not teach”.
Mrs Garner questioned Mr Rycroft’s attempts to help her, claiming that he and another teacher had not followed school policy when taking action against misbehaving pupils.
She also claimed that Mr Rycroft and the senior management team at Alva Academy failed to follow up on pupils who had received referrals for misbehaving.