Pam Allen claims the isolation room at St Helena's School in Colchester contravenes pupils' human rights.
The room is used as a punishment for bad behaviour, and pupils sent to it are subjected to a six hour session with 20 minutes for lunch.
Ms Allen removed her daughter - whose identity has been protected - from school eight months ago after she was put in the room.
Ms Allen told the Daily Gazette that putting kids in the unit was tantamount to 'abuse', saying 'I don't want my daughter to go to a school with an isolation unit. It is abuse.'
The family were told the teenager would not allowed back into school until she had completed her period of isolation. Her furious mum said she was 'really very angry' at this decision, as despite the school's claims the girl was truanting, she was in fact off sick.
Ms Allen has now asked her local authority to pay for private tutoring for her daughter.
Essex County Council are reportedly looking into study options while the girl is at home, but Ms Allen said the council's refusal to give her the money meant her daughter was missing out on her final year of an education.
She said: 'My daughter can't do her GCSEs now because she has not done the coursework. I have been threatened with a court order. But I am prepared to go to jail on this.'
A spokesperson for Essex County Council spokesperson said they were unable to comment on the case.
What do you think? Do you agree with this mum's stance, or do you think they should just suck up the punishment and get the teenager back into education?