Berthelot Dartigny was named judge of the Court of Common Pleas for Quebec district in 1791.
He ran unsuccessfully for a seat in the Legislative Assembly of Lower Canada for Quebec County in 1792; he was declared elected in 1793 when Ignace-Michel-Louis-Antoine d'Irumberry de Salaberry chose to represent Dorchester in the assembly.
He was elected to represent Kent in a 1798 by-election after the death of the previously-elected member, then elected in Quebec County in 1800 and 1804.
Berthelot Dartigny opposed the bill which disallowed judges from sitting in the assembly.
He died at Quebec City in 1815.
His son Amable Berthelot was also a lawyer and a member of the legislative assembly.
A park and street in Quebec City were named Berthelot
and another street was named D'Artigny after Michel-Amable Berthelot Dartigny.