Why the Constitution points to 16 votes, why the current absences created a real dispute, and why the Senate must settle the counting rule before judgment.
The Constitution says Vice President Sara Duterte cannot be convicted unless two-thirds of all Senate members vote for conviction. In a full 24-member Senate, that means 16 votes. The dispute is whether the number must remain 16 when some senator-judges cannot take part.
That is no longer a theoretical question. Jinggoy Estrada and Rodante Marcoleta are detained, Ronald dela Rosa is in hiding, and Loren Legarda is on medical leave abroad. Senator-judge Erwin Tulfo has asked the impeachment court to reconsider its fixed-16 ruling. The Senate plans to hear independent legal experts on September 16, hear both sides on September 23, and vote on the issue afterward.
This is not a vote on Duterte's guilt. It is a decision about how the final vote will be counted. Here are the five points that should guide it.