Although a decisive political victory had been gained, and a responsible government formed, by Louis-Hippolyte Lafontaine and Robert Baldwin in 1848, they did not press for an immediate overthrow of existing institutions, and in 1851, the administration was handed over to Francis Hincks and Augustin-Norbert Morin.

It seemed that the coalition government under Allan MacNab had clarified the situation, but by 1856 Upper Canada had increased, and it contributed a larger share to the revenue, and demanded proportionate representation.

Dorion understood the true principle of federation as applicable to Canada, but he did not pursue this idea, and in fact his following was never sufficiently strong to enable him to give effect to the sound measures he was so capable of formulating.

[2] In 1858 Dorion served as Co-Premier of the Province of Canada with Clear Grit leader George Brown (Canadian politician) but the government fell within three days.

He was re-elected three times in succession for Napierville and served as Minister of Justice in the Liberal government of Alexander Mackenzie from 7 November 1873 and during the six months that he was in office passed the Electoral Law of 1874 and the Controverted Elections Act.