In a series of cases, beginning with Addyston Pipe & Steel Co. v. United States,41 the court has shown that combinations or agreements between manufacturers or dealers do not come within the protection of the doctrine of the Knight case if it appear that the attempt is made in any way directly to control or change what would normally be the course of interstate commerce in the absence of such combinations or agreements.

In the Addyston case six companies, engaged in the manufacture and sale of iron pipe, had formed a combination whereby competition in the sale of pipe throughout the United States was practically destroyed. In the exercise of the power thus possessed, the combination had allotted to its several member companies the territory within which each should have the exclusive right to sell its products. By a unanimous opinion the court held the agreement to come within the prohibition of the act of 1890. Distinguishing this combination from that in the Knight case, the court say: " The direct purpose of the combination in the Knight case was the control of the manufacture of sugar. There was no combination or agreement in terms regarding the future disposition of the manufactured article; nothing looked to a transaction in the nature of interstate commerce." As to the Addyston combination, the court say: " The direct and immediate result of the combination was . . . necessarily a restraint upon interstate commerce in respect of articles manufactured by any of the parties to it to be transported beyond the State in which they were made. The defendants, by reason of this combination and agreement, could only send their goods out of the State in which they were manufactured for sale and delivery in another State, upon terms and pursuant to the provisions of such combination."

40 171 U. S. 604; 19 Sup. Ct. Rep. 50: 43 L. ed. 300. 41 75 U. S. 211; 20 Sup. Ct. Rep. 96; 44 L. ed. 136.