The Forum for Rights and Equality said the judgement is against the spirit of the Constitution and has attacked the concept of reservation.
The Supreme Court on July 18 had ruled that there can be no reservation in appointment for faculty posts in speciality and super speciality courses in medical colleges, including the prestigious AIIMS.
A five-judge constitutional bench headed by the then Chief Justice Altamas Kabir had said it cannot take a contrary view expressed in 1992 by a nine-judge bench in the Indra Sawhney case, also known as the Mandal case, that there could be no compromise with merit at the super speciality stage.
Asserting that reservation is "not at all anti-meritarian in any manner", the forum said the apex court's verdict could have "detrimental and dangerous consequences not only for the reservation in favour of SCs, STs and OBCs but also in favour of women, children and disabled categories".
"Any delay or failure in reversing and correcting this wrong declaration would make the Constitution a matter of international ridicule and a tool of oppression and casteist suppression," the letter said.