He was called to the Quebec Bar in 1864 and practiced law with future Premier of Quebec Joseph-Alfred Mousseau until 1872.
In 1862, David became a co-owner and editor of the newspaper the Colonisateur.
After the paper ceased publication he became an editor with the paper,
L’Union nationale, an antifederalist newspaper which would cease publication in 1867.
It was while working at this newspaper that he established a friendship with Wilfrid Laurier which would continue until the end of Laurier's life.
He unsuccessfully ran for the Legislative Assembly of Quebec for the electoral district of Hochelaga in the 1867 election and again in 1875.
From 1870 to 1873, he was the editor-in-chief of the Montreal weekly newspaper L’Opinion publique.
From 1874 to 1876, he was a co-founder and co-owner of the Le Bien public.
In 1878, he was an unsuccessful Liberal candidate for the House of Commons of Canada for the electoral district of Hochelaga.
In 1890, he was made a Fellow of the Royal Society of Canada.
From 1892 to 1918, he was a clerk for the Montreal City Council.
He was called to the Senate of Canada for the senatorial division of Mille Isles on the advice of Wilfrid Laurier in 1903.
He served until his death in 1926.
He was awarded the Bene merenti de patria in 1924.
His son Louis-Athanase David and his grandson Paul David both also became senators.
Author: H. Larin Source: Parliament of Canada website Page Source, which sources it to Library and Archives Canada, Negative number C-015879 Notice from LAC License: CC-PD-Mark PD Old