US Presidency
1850

It is plain, therefore, on the face of these treaty stipulations that all Mexicans established in territories north or east of the line of demarcation already mentioned come within the protection of the ninth article, and that the treaty, being a part of the supreme law of the land, does extend over all such Mexicans, and assures to them perfect security in the free enjoyment of their liberty and property, as well as in the free exercise of their religion; and this supreme law of the land, being thus in actual force over this territory, is to be maintained until it shall be displaced or superseded by other legal provisions; and if it be obstructed or resisted by combinations too powerful to be suppressed by the civil authority the case is one which comes within the provisions of law and which obliges the President to enforce those provisions. Neither the Constitution nor the laws nor my duty nor my oath of office leave me any alternative or any choice in my mode of action.