On September 23, 2014, he was found guilty of gross misconduct, dishonesty and impropriety and was subsequently dismissed from his position as Justice of the Sandiganbayan by the Supreme Court of the Philippines as a result of an investigation linking him to pork barrel scam mastermind Janet Lim-Napoles.
[2][3] Ong finished elementary and high school education at the Philippine Chinese Chen Kuang (1966) and at the Jose Rizal College (with honors, 1970), respectively.
Azcuna wrote that Ong would be unable to join them on the bench "until he had proven in court that he was a natural-born Filipino citizen and corrected the records of his birth and citizenship".
[7][8] The court voted 13–0 in favor of petitioners Kilosbayan and Bantay Katarungan foundations (Senate President Jovito Salonga and Emilio Capulong).
[10] On July 26, 2007, retired Supreme Court Justice Vicente Mendoza, a noted constitutionalist, said that there was no vacancy at the moment since the President had already appointed Ong.
Mendoza said there was no declaration that Ong was not a natural-born Filipino and he was given a chance to file a correction of entry via adversarial proceedings in the regional trial court.
[12] On September 28, 2007, Gregory Ong filed a seven-page comment (to the administrative complaint of Special Prosecutor Dennis Villa-Ignacio) with the Supreme Court of the Philippines.
The Civil Registrar of San Juan, Metro Manila was directed to annotate in the Certificate of Birth of Ong the decision.
[16] On December 4, 2007, the oppositions Kilosbayan and Bantay Katarungan headed by Jovito Salonga stated that Judge Janolo denied their motion for reconsideration, and they appealed to the High Court to reverse the lower court's decision on account of “grave error.” The High Tribunal has yet to resolve 2 separate pleadings filed before it regarding Ong's citizenship: a) the letter-query of Special Prosecutor Dennis Villa-Ignacio on Ong's status as Sandiganbayan justice, and b) the Quo Warranto petition filed by Iglesia ni Cristo lawyer Ferdinand Topacio, who asked the Court to stop Ong from exercising his role as Sandiganbayan justice because of his questionable citizenship.
[1] Following the testimony of Pork Barrel Scam whistleblower Benhur Luy to the Philippine Senate tagging Ong as the main contact into the Sandiganbayan of Pork Barrel Scam mastermind Janet Lim-Napoles, Chief Justice Maria Lourdes Sereno ordered for an investigation that subsequently found credence in Luy's accusations.
[18] With the Court voting 8-5 (with two abstentions), the ruling found Ong "guilty of gross misconduct, dishonesty and impropriety under the new code of judicial conduct for the Philippine judiciary."