Quote from : Star Wars: Episode III - Revenge of the Sith Movie

Mace Windu: In the name of the Galactic Senate of the Republic, you're under arrest, Chancellor.
Supreme Chancellor: Are you threatening me, Master Jedi?
Mace Windu: The senate will decide your fate.
Supreme Chancellor: [now speaking as Darth Sidious] I AM the senate!
Mace Windu: Not yet.
[the Chancellor/Darth Sidious rises slowly, and his lightsaber snaps to his hand from his sleeve]
Supreme Chancellor: It's treason, then...
[ignites his lightsaber and leaps over his desk to attack]