Based on an appeal filed by the socio-political organization, Rashtriya Mukti Morcha (RMM), the petition challenged a Delhi high court order dismissing a petition that had questioned Congress chief Sonia Gandhi being invited to form the government in 1999 by the then President. [UPDATE: Sonia Gandhi in trouble, Obama to exclude Cong Prez from US?]
Back in 2007, the Supreme Court had issued a notice to the Centre and the Election Commission on the matter. The Centre did not file an affidavit on the case and asked the apex court to post the matter for final hearing. The Election Commission had said that its stand would be the same as that of the Centre.