So long as the Senate watches over her, Archadia's well-being will ever be assured.
The Imperial Senate is the main political body of the Archadian Empire in Final Fantasy XII. 200 years before the start of the game, the Senate was actively engaged in the rule of Archadia before the rising power of the military caused a turn towards an imperial system.
While the emperors ruled the nation with the power of the Judges, the Senate, now a mere rubber stamp council, remains in the capital of Archades, having little role other than to scheme against the head of state as they cannot hope to pass legislation that does not have support of the Emperor or the Judges.
The Senate fears the rising strength of the young and ambitious heir to House Solidor, Vayne, and so moves to have him executed for treason, citing the loss of the 8th Fleet of the Imperial Army. In his place they hope to prop up the child Larsa. Vayne comes to Archades to confront his father, Emperor Gramis, but finds that the elderly and sickly emperor prefers Larsa.
In a single move, Vayne destroys his enemies: he kills his father and then blames the crime on the head of the Senate Chairman Gregoroth. Using the Judges, Vayne has the entire Senate arrested, giving him complete control over the whole of the Archadian Empire. Judge Drace alone attempts to stop this coup d'etat, but she is executed on the spot by her fellow Judges.
The further fate of the Senate is never revealed, and it is unknown if the body was ever restored.