Sally Brown, 45, was refused sick pay when she injured her neck working for the Granta Housing Society. She helped with the care of mentally ill people full-time for nine months but in June 1992 she was off work for nearly six months.
Granta refused her sick pay because they claimed she was employed on a series of daily contracts.
Their decision was upheld by the Department of Social Security and a social security commissioner who decided Ms Brown was no longer employed after the day she became sick and was sent home.
But Lord Justice Nourse said that because Ms Brown, of Cambridge, had "continuity of employment" for more than three months, her contract had become indefinite under the Employment Protection Act .
She was supported in her action by the CPAG Cherie Booth QC, who had argued in the appeal court that the legislation meant Ms Brown's contract continued throughout the period she was sick and she was entitled to statutory sick pay.
David Thomas, CPAG's legal officer, said after the hearing: "This is an important decision not just for people in Sally's position but for other casual workers too.
"More and more people are forced to work on a casual basis and it is clearly unacceptable if they lose their rights as a result. The decision shows that they need not.
"Sally was to all intents and purposes a permanent employee and the court has confirmed that her employers should not be able to escape their obligations simply by using the device of a series of daily contracts."
Ms Brown's fight for an estimated pounds 1,200 sick pay must go back to the Social Security Appeals Tribunal with a direction for the Appeal Court judges to reconsider the case in the light of their decision.Reuse content