The family moved in 1812 to Montreal in Lower Canada, where his father was involved in retail businesses, particularly pharmacies and provisions for the fur trade.

[1][2] Day’s political career began in 1834, when he spoke publicly against the Ninety-Two Resolutions, passed by the Legislative Assembly of Lower Canada.

[2] Day spoke strongly in favour of maintaining the British connection and opposed what he saw as a revolutionary approach in the Resolutions.

He also was elected to a significant position on a committee formed to draft an address to the monarch and the British government outlining the political views of the anglophone business community in Montreal.

He was supported by Ottawa timber merchants such as Ruggles Wright, and campaigned in favour of the union of the two Canadas.

Baldwin's focus was on instituting a system of responsible government, where the Governor General would appoint the Executive Council from the group with a majority in the Legislative Assembly.

As part of that policy, Baldwin wanted to ensure francophone Reformers from Lower Canada would be in the Council.

Baldwin wrote to Sydenham, protesting the inclusion of Day and other Government Tories, and the exclusion of French-Canadian representatives.

The following year, in 1842, the new governor general, Sir Charles Bagot, was trying to reconstruct the ministry to better reflect the composition of the Legislative Assembly.

his resignation created a vacancy in the Executive Council, but Bagot had trouble finding a French-Canadian to fill the position.

Day was the main author of the portion of the proposed code dealing with commercial law, which was his legal specialty.

His work became the fourth book of the Civil Code of Lower Canada, entitled "Commercial Law".

By a statute passed in 1865, the Parliament approved the draft code, with a number of corrections and additions for the commissioners to review.

[16] In 1866, the provincial Cabinet passed an order-in-council authorising the Governor General to proclaim the Code in force on August 1, 1866.

[15] By the time of its enactment, shortly before Confederation in 1867, the Code was seen as an important statement of Quebec's control over its own legal system in the new country.

[1][2][19] In 1869, Day was retained by the Hudson's Bay Company to argue its case before the British-American Joint Commission appointed under a treaty between the two countries, signed in 1864, respecting property claims in the Oregon country (referred to as the Columbia district by Britain).

[22] In 1873, Day was appointed chair of the Royal Commission which investigated charges of corruption against the federal government in the Pacific Scandal.

The commission’s mandate was to investigate allegations that the Conservatives under Prime Minister Sir John A. Macdonald had agreed to give the contract for the Canadian Pacific Railway to Sir Hugh Allan, owner of the Allan steamship line, in exchange for substantial campaign donations to the Conservatives in the 1872 federal election.

[27] The commission did not make any findings, but simply filed the transcripts of the evidence with Parliament, when it returned following a prorogation.

[28] Dufferin concluded that the evidence cleared Macdonald of personal corruption, and of any knowledge of the key point, that Allan had covert arrangements with American financiers for control of the proposed railway.

However, on one point, Macdonald admitted that the Conservatives had used some of the money received from Allan for improper election expenses.