The church has sacked a religious education teacher because she married a man who was divorced.
The move has been condemned by trade unions.
Resurreccion Galera Navarro, 36, was called by bishop of Almeria on May 8 and told to leave her job at a Catholic school in Andalucia,southern Spain, immediately - and silently.
The bishop told the teacher:"We have been told that you are living with a married man. The situation is unsustainable."
The teacher, a practising Catholic, had worked as a religious teacher in the school for seven years. But in spring 1999 she fell in love with Johannes Romes, a German who had divorced in 1975 and had been waiting for his marriage to be annulled by the church.
A year later the couple married in a civil ceremony. When she was told to leave by the bishop she refused because it appeared to her "inhuman" to leave the children suddenly without finishing the course. Instead she decided to campaign to change the legl position of religious teachers in Spain.
Under an agreement between the state and the Vatican, Spain's 13,000 RE teachers are employed and paid for by the state, but they are proposed annually by the church. The church say this agreement gives the church the power to decide who gives religious education in Spain. The Popular Party, currently in power, has no plans to change the agreement.
Union leaders said the agreement was "almost feudal" saying that the church is imposing working conditions that are "an attack against the fundamental rights of the person". They say that the annual selection process makes the church "the biggest temporary employer in Spain".
The 500 students in the school marched in support of their former teacher last week.
The couple plan to take legal action if her name does not appear on the church's list in June. "We are waiting to see what the church is going to do," said her husband. "The ball is now in its court."