How did the case United States v. E. C. Knight weaken the Sherman Antitrust Act?

The case United States v. E. C. Knight weakened the Sherman Antitrust Act, because the Sherman Antitrust Act reduced competition between companies, because it did not want power to erupt from this. United States vs. E. C. Knight limited the government's power to monopolize companies in this way. The outcome of the case was that manufacturing cannot be regulated by Congress.