[DuncanWaring]

2/3 of “those present”.

A quorum is 51.

Could theoretically be ratified, on the sly, by 34 traitors.

[OneWingedShark]

2/3 of “those present”.
A quorum is 51.
Could theoretically be ratified, on the sly, by 34 traitors.

Except that "those present" doesn't indicate a quorum, you could have 0 present.
There's a paper which details that necessity to make treaties in secret.