How did the Supreme Court limit the scope of the Sherman Antitrust Act?

It allowed the Sherman Antitrust Act to affect and preempt a state law under congress jurisdiction, and subjected to the conclusion of a two-step examination, as set forth by the Supreme Court in the Rice vs. Norman Williams Company case.

The Supreme Court allowed the Sherman Antitrust Act to preempt a state law, subject to the results of a two-step analysis, as set forth by the Supreme Court in Rice v. Norman Williams Co.