New Delhi, Aug 18 - The Supreme Court Tuesday began examining if Dalit and backward category students competing in the civil services examination without availing quota benefits should be allowed to use reservation to secure higher services and better cadre.

A five-judge constitution bench, headed by Chief Justice K.G. Balakrishnan, began examination of the crucial issue relating to reservation in civil services for candidates belonging to Scheduled Castes, Scheduled Tribes and the socially and educationally backward sections of society on a bunch of lawsuits, including one by the union government.

The union government's lawsuit challenged a March 2008 ruling of the Madras High Court which held that Dalit and backward category students, competing on merit, cannot be given the benefit of reservation for allocation of higher service and better cadre in the civil services.

The union government approached the apex court on May 17 last year, challenging the high court ruling. The apex court suspended the ruling two days later.

The apex court had decided May 14 this year to refer the matter to a five-judge constitution bench for examination.

The high court had held that if a meritorious Dalit or backward category student is allowed to avail the quota benefits during the stage of allocation of services and cadre, it would impinge upon the rights of other such students who were able to clear the examination using the reservation benefits.