He resigned his position in the militia after a number of his friends were dismissed as militia officers because of their association with the Patriotes.
Girouard was elected to the Legislative Assembly of Lower Canada for Deux-Montagnes in an 1831 by-election held after the death of Jacques Labrie and supported Louis-Joseph Papineau in the assembly.
He supported the Ninety-Two Resolutions and was reelected in 1834.
In 1837, his name was on a list of rebel leaders to be arrested.
He escaped but later turned himself in after he heard that his supporters had already been arrested and was imprisoned at Montreal.
He was released in July 1838 but imprisoned again following the uprisings later that year.
After his release, he retired from politics and returned to his profession as a notary.