Two interpreters, who were paid £25,000 to "do nothing" for 15 years, stand to win £1 million in compensation from the Home Office.
The Central London Employment tribunal found that Marti Khan and Odette King, who are seeking 970,000 and 682,000 respectively, had been subjected to sexual and race discrimination.
The women were employed to work 41 hours per week at Heathrow Airport to translate for new arrivals from India.
But when outsourced staff began to be used for translation in 1990 the women were not reassigned and were instead charged with menial administration work until they were sacked in 2001 after making a complaint.
Commenting on the ruling Mrs King said: "As two ethnic minority women we were treated badly and the department was like a ghetto. We did not have access to facilities that were given to all other members of staff.
"It went on until I just could not turn up at work and face anybody. My confidence was shot to pieces. I did not even know if I could function as an interpreter any more," she added.
The women, who claim that their careers have been ruined, are also seeking a ruling that the Home Office must find them new jobs.