Lapointe earned his law degree from Laval University. He was a practicing lawyer in Quebec City, and was appointed Crown Prosecutor for Kamouraska before entering politics.
In 1921, Prime Minister William Lyon Mackenzie King appointed Lapointe to his first Cabinet as Minister of Marine and Fisheries. During his term as minister of fisheries, he negotiated a treaty with the United States on west-coast fishing rights. This was the first time that a Canadian minister negotiated on foreign affairs without any assistance from Great Britain. In 1924 he became Minister of Justice, and served in that position in successive Liberal cabinets until his death in 1941.
Lapointe served as King's Quebec lieutenant and was one of the most important ministers in Cabinet. King did not speak French; he relied on Lapointe to handle important matters in the province. Lapointe gave a strong Quebecker voice to the cabinet decision, something that had not existed since the defeat of Laurier in 1911. Lapointe shared King's vision of Canadian autonomy from Britain, and chaired the Canadian delegation to the Imperial Conference of 1926. This led to the drafting of the subsequent Balfour Declaration that raised the status of dominions to one of equality with Britain, and eventually led to the Statute of Westminster 1931. In the late 1930s, Lapointe recommended that the federal Cabinet disallow several Acts passed by the Alberta Social Credit government of William Aberhart. However, he did not recommend disallowance of the Padlock Act passed by the Quebec government of Maurice Duplessis, fearing that doing so would only aid the Union Nationale government.
Conscription issue
Lapointe helped draft Mackenzie King's policy against conscription for overseas service in 1939, and his campaigning helped defeat the Duplessis provincial government in 1939. During the 1939 election, Lapointe made many speeches in the province of Quebec, in which he argued that if Duplessis was to be re-elected, every French Canadian minister would resign from the federal cabinet, leaving it without a francophone voice. Having been a Liberal MP during the 1917 conscription crisis, Lapointe knew how much a new crisis like the last one would destroy the national unity that Mackenzie King had tried to build since 1921.
