In order to make the louisiana purchase, what justification did the government use?

In order to make the Louisiana Purchase, the government argued that the power of purchasing territory, although not written in the Constitution, was an implicit power that the President had.

Explanation:

The Louisiana Purchase in 1803 for 15 million dollars required Jefferson to resort to the implied powers, demanding an extraordinary increase in spending and the justification of an apparent federal overreaching of his constitutional powers: it was questioned whether the purchase of territory by the federal government could be made, and if this could unilaterally grant citizenship to its inhabitants. The contradictions could be overcome with the approval of the Senate of the Purchase Agreement, which doubled the US territory in a stroke; with this, the power of the Jeffersonians was strengthened and secessionist whims in New York and New England awoke against them. There they already feared the loss of their political and economic influence in the country as a whole, as a result of the predictable agrarian expansion to the west, under the control of the Republican Democrats of Jefferson.

the social contract theory