I have seen over and over a distinction made in period writings. So, just WHEN was common law integrated into American law, and just WHEN did we cease using English law? According to you?
There wasn’t one date when we suddenly switched to all USA common law. Even now, in an obscure matter, one might cite an English court case from before the Constitution...as WKA did at length, as here:
“This fundamental principle, with these qualifications or [p656] explanations of it, was clearly, though quaintly, stated in the leading case, known as Calvin’s Case, or the Case of the Postnati, decided in 1608, after a hearing in the Exchequer Chamber before the Lord Chancellor and all the Judges of England, and reported by Lord Coke and by Lord Ellesmere. Calvin’s Case, 7 Rep. 1, 4b-6a, 18a, 18b; Ellesmere on Postnati, 62-64; S.C., 2 Howell’s State Trials, 559, 607, 613-617, 639, 640, 659, 679.
The English authorities ever since are to the like effect. Co.Lit. 8a, 128b, Lord Hale, in Hargrave’s Law Tracts, 210, an in 1 Hale P.C. 61, 62; 1 Bl.Com. 366, 369, 370, 374; 4 Bl.Com. 74, 92; Lord Kenyon, in Doe v. Jones, 4 T.R. 300, 308; Cockburn on Nationality, 7; Dicey Conflict of Laws, p. 173-177, 741.
In Udny v. Udny, (1869) L.R. 1 H.L. Sc. 441, the point decided was one of inheritance, depending upon the question whether the domicil of the father was in England or in Scotland, he being in either alternative a British subject. Lord Chancellor Hatherley said: “The question of naturalization and of allegiance is distinct from...”
Again, for the purposes of this argument, what is important is this:
“The interpretation of the Constitution of the United States is necessarily influenced by the fact that its provisions are framed in the language of the English common law, and are to be read in the light of its history.”
http://supreme.justia.com/cases/federal/us/124/465/case.html