How did the case United States v. E.C. Knight weaken the Sherman Antitrust Act? The Supreme Court ruled that the American Sugar Company was a legal monopoly since it existed only in one state. The Supreme Court ruled that the American Sugar Company was a legal monopoly since it operated in several states. The Supreme Court ruled in favor of the American Sugar Company since it controlled only fifty percent of the sugar-refining factories. The Supreme Court ruled against the American Sugar Company since it controlled ninety-eight percent of the sugar-refining factories.