The Royal School Dungannon has been found guilty of sex discrimination against one of its senior women teachers, it was announced today.
A woman head of department took the leading grammar school to an industrial tribunal because it paid her less than other male heads of department, and she claimed it was because she was a woman.
The Equality Commission and the teacher's union supported her case.
The tribunal found in her favour and that the school had failed to explain the difference in pay between Pamela McMullan, head of the Food Technology Department and the male head of the Design and Technology Department.
Mrs McMullan celebrated her victory and said she hoped other teachers would not have to go through the same battle.
She said: "I am very relieved that this is over. I have not allowed this to impact on my day to day work and continue to enjoy teaching my pupils and interacting with my colleagues.
"I am glad that with the support of my union, the Association of Teachers and Lecturers and the Equality Commission, the point has been proved and I hope that other teachers will not have to go through the same thing."
Mrs McMullan claimed she was engaged in the same sort of broadly similar work to three other heads of department in the school and that she was paid less than them on the grounds of her sex.
The tribunal examined the duties, volume of work and levels of responsibilities of all four teachers and took into consideration the changing advice from the Department of Education governing the award of teaching allowances.
It concluded that "Mrs McMullan's work as head of the Food Technology Department is of the same or broadly similar nature to that of the three males head of department."
While the tribunal found that the responsibilities of two of the male heads explained the difference in pay, it found the school failed to explain the difference in pay between Mrs McMullan and the third head of department.
It stated: "The evidence is clear that Mrs McMullan has greater responsibility than the head of Design and Technology Department in terms of GCSE and A level pupils, equivalent full-time teachers, number of periods taught per week and supervision of non-teaching staff."
It concluded: "Although the tribunal accepts that he has more extensive involvement in extracurricular after school and weekend activities than the claimant, the respondent failed to explain how it assessed Mrs McMullan's higher level of departmental responsibilities with the Head of Design and Technology Department's higher level of extracurricular activities."
Eileen Lavery, the Equality Commission's head of strategic enforcement said: "We are very pleased that the tribunal is reinforcing the right to equal pay for work of equal value.
"What the case underlines is the need for employers to have a fair and transparent pay policy."
She said criteria for factors to be taken into account in relation to matters such as responsibility points should be clearly established and objectively applied.
"All employers have a legal duty to avoid discrimination on grounds of gender."
Mark Langhammer, ATL union's Northern Ireland director, said they were delighted Mrs McMullan had won her case after a long fight.
"It was patently unfair for her to be paid less than a male head of department with similar responsibilities.
"Schools must have clear and transparent salary policies, and must apply them fairly. If they don't we will fight to make sure they change their ways," he said.
Mr Langhammer added: "Teachers should take heart that equal pay cases are winnable, and should not be scared to stand their ground if they are being treated unfairly."
How the matter is to be remedied is yet to be determined, said the Equality Commission.
The school said it was making no comment "because the matter is still receiving legal consideration."