MIRIAM DEFENSOR SANTIAGO, ALEXANDER PADILLA AND MARIA ISABEL ONGPIN, PETITIONERS, VS. COMMISSION ON ELECTIONS, JESUS DELFIN, ALBERTO PEDROSA & CARMEN PEDROSA, IN THEIR CAPACITIES AS FOUNDING MEMBERS OF THE PEOPLE’S INITIATIVE FOR REFORMS, MODERNIZATION AND ACTION (PIRMA), RESPONDENTS, SENATOR RAUL S. ROCO, DEMOKRASYA-IPAGTANGGOL ANG KONSTITUSYON (DIK), MOVEMENT OF ATTORNEYS FOR BROTHERHOOD INTEGRITY AND NATIONALISM, INC. (MABINI), INTEGRATED BAR OF THE PHILIPPINES (IBP) AND LABAN NG DEMOKRATIKONG PILIPINO (LABAN), PETITIONERS-INTERVENORS