SC petitions to impeachment vote rule a ‘litmus test’ — Adiong. MANILA, Philippines — The Supreme Court challenges to the Senate impeachment court’s new voting rule will be a “litmus test” of how the Constitution’s accountability mechanism applies under unprecedented circumstances, trial spokesperson and Lanao del Sur Rep. Zia Alonto Adiong said Saturday. “It’s a litmus test because I believe the Constitution is very expressive, explicit.