Webster also dealt with the problem which arises when Congress has exercised its power. The results of its act, he contended, must be treated as a unit, so that when Congress had left subject matter within its jurisdiction unregulated, it must be deemed to have done so of design, and its omissions, or silences, accordingly be left undisturbed by State action. Although Marshall, because he thought the New York act creating the Livingston-Fulton monopoly to be in direct conflict with the Enrolling and Licensing Act of 1793, was not compelled to pass on either of Webster's theories, he indicated his sympathy with them.[528] COOLEY _v._ BOARD OF PORT WARDENS Aside from Marshall's opinion in 1827 in Brown _v._ Maryland,[529] in which the famous "original package" formula made its debut, the most important utterance of the Court touching interpretation of the commerce clause as a restriction on State legislative power is that for which Cooley _v._ Board of Wardens of Port of Philadelphia,[530] decided in 1851, is usually cited. The question at issue was the validity of a Pennsylvania pilotage act so far as it applied to vessels engaged in foreign commerce and the coastwise trade. The Court, speaking through Justice Curtis, sustained the act on the basis of a distinction between those subjects of commerce which "imperatively demand a single uniform rule" operating throughout the country and those which "as imperatively" demand "that diversity which alone can meet the local necessities of navigation," that is to say, of commerce. As to the former the Court held Congress's power to be "exclusive"--as to the latter it held that the States enjoyed a power of "concurrent legislation." While this formula obviously stems directly from Webster's argument in Gibbons _v._ Ogden, it covers considerably less ground. Citation, nevertheless, of the Cooley case throughout the next half century eliminated the difference and brought the Curtis dictum abreast of Webster's earlier argument. The doctrine consequently came to be established, _first_, that Congress's power over interstate commerce is "exclusive" as to those phases of it which require "uniform regulation"; _second_, that outside this field, as plotted by the Court, the States enjoyed a "concurrent" power of regulation, subject to Congress's overriding power.[531] JUDICIAL FORMULAS