In Lehigh Valley Railroad Co. v. Pennsylvania [1] (upon which, as has been said, Mr. Wallace relied) the relevant railroad lay wholly within Pennsylvania except that it seems to have crossed an "inter-state bridge" to and from a town on the bank of the river on the New Jersey side. What was challenged in the case was the validity of a State tax. The State sought to impose its tax only in respect of that proportion of the total length of the railroad in question which lay within Pennsylvania. The tax was held to be valid. In delivering the opinion of the Court Fuller C.J. said: - "The tax under consideration here was determined in respect of receipts for the proportion of the transportation within the State, but the contention is that this could not be done because the transportation was an entire thing, and in its course passed through another State than that of the origin and destination of the particular freight and passengers. There was no breaking of bulk or transfer of passengers in New Jersey. The point of departure and the point of arrival were alike in Pennsylvania. The intercourse was between those points and not between any other points. Is such intercourse, consisting of continuous transportation between two points in the same State, made interstate because in its accomplishment some portion of another State may be traversed? Is the transmission of freight or messages between two places in the same State made interstate business by the deviation of the railroad or telegraph line on to the soil of another State?" [1] . And he answered these questions in the negative. This case might well be thought at first sight to support the view that the journey from Talyealye to Sydney ought to be regarded as an intra-State journey for the purposes of s. 92. But the Lehigh Valley Case [2] was, I think, placed on its true basis, and the passage quoted above deprived of any authoritative effect, by Frankfurter J. in delivering the opinion of the Court in Central Greyhound Lines Inc. v. Mealey [3] . The learned judge said: - "It was reasonable enough to disregard the short distance in which the transportation in the Lehigh Valley Case went over the interstate bridge on the Delaware River but otherwise was wholly in Pennsylvania, and to treat it as de minimis when the railroad's accounting itself treated the receipts as proportioned. "Regulation and commerce among the States both are practical rather than technical conceptions, and, naturally, their limits must be fixed by practical lines." Galveston, Harrisburg and San Antonio Railway Co. v. Texas [4] . But to label transportation across an interstate stream "local commerce" for some purposes when it is "inter-State commerce" in other relations, see, e.g., Covington & Cincinnati Bridge Co. v. Kentucky [5] , is to use loosely terms having connotations of constitutional significance. To call commerce in fact interstate "local commerce" because under a given set of circumstances, as in the Lehigh Valley Case [2] , a particular exertion of State power is not rendered invalid by the Commerce Clause is to indulge in a fiction. Especially in the disposition of constitutional issues are legal fictions hazardous, because of the risk of confounding users and not merely readers. The kind of confusion to which the Lehigh Valley [1] opinion has given rise results from employing a needless fiction - calling commerce local which in fact is interstate - as a manner of stating that a particular exercise of State power is not invalid even though it affects inter-State commerce. The difficult task of determining whether a phase of commerce, concededly interstate, is subject to a particular incidence of State regulation, through taxation or otherwise, is not lessened by calling interstate commerce local commerce in order to sustain its local control. To state this persistent and protean problem of our federalism in the form of a question-begging fiction, is not to answer it" [2] . Frankfurter J. said a little later: - "We are not dealing with a necessary deviation or a calculated detour" [3] . But I would not regard the Queensland part of the journey in the present case as either a deviation or a detour.