Independently of any effect due to the compact as such, a boundary line between States or provinces, as between private persons, which has been run out, located and marked upon the earth, and afterwards recognized and acquiesced in by the parties for a long course of years, is conclusive, even if it be ascertained that it varies somewhat from the courses given in the original grant; and the line so established takes effect, not as an alienation of territory, but as a definition of the true and ancient boundary. Lord Hardwicke in Penn v. Lord Baltimore [30] ; Boyd v. Graves [31] ; Rhode Island v. Massachusetts [32] ; United States v. Stone [33] ; Kellogg v. Smith [34] ; Chenery v. Waltham [35] ; Hunt on Boundaries, 3d ed., p. 306.
These principles are analogous to the doctrine of adverse possession established in the common law at least since the Statute 21 Jac. 1 c. 16: possession for 20 years is "proof of seisin" (see, generally, Buller's Nisi Prius, 4th ed. (1785), p. 103; Holdsworth, A History of English Law, vol. VII 2nd ed., p. 64;Doe d. Lewis v. Davies [36] , per Parke B.). However, in relation to the boundaries of former colonies the courts both in the United Kingdom and the United States have regarded it as necessary that there should be an acquiescence by one side in the claims of the other as well as an assertion and exercise of sovereignty by the other for a long period (see Direct United States Cable Co. v. Anglo-American Telegraph Co. [37] and Arkansas v. Tennessee [38] and cases there cited). We need not consider whether for this purpose acquiescence and prescription should properly be regarded as separate doctrines (a view which appears to be taken by Blum, Historic Titles in International Law, (1965) pp. 29-31) or whether acquiescence is one of the elements necessary for the acquisition of prescriptive title (which seems to be the view of Professor O'Connell, International Law, 2nd ed., (1970), vol. 1, pp. 423-424, and MacGibbon, The Scope of Acquiescence in International Law, British Yearbook of International Law, vol. 31 (1954), 143, at pp. 182-183 ). In the present case there was acquiescence as well as assertion of power and jurisdiction for a long period.
1. (1893) 148 U.S. 502, at pp. 522-523 [37 Law. Ed. 537, at p. 544].
2. (1910) 217 U.S. at p. 42 [54 Law. Ed., at p. 658].
3. (1750) 1 Vesey Sen. 444, at p. 448.
4. (1819) 4 Wheat. 513.
5. (1838) 12 Pet. 657, at p. 734.
6. (1865) 2 Wall. 525, at p. 537.
7. (1851) 7 Cush. 375, at p. 382.
8. (1851) 8 Cush. 327.
9. (1837) 2 M. & W. 503, at p. 516 [150 E.R. 856, at p. 862].
10. (1877) 2 App. Cas. 394, at pp. 420-421.
11. (1940) 310 U.S. 563, at pp. 569-570 [84 Law. Ed. 1362, at p. 1366].