"Varney seems to be saying 'we're going to do a straight balancing test, ' " said Mr. Schildkraut.

WSJ: Sherman Stirs: U.S. Revives Section 2 of the Antitrust Act

Still, said Mr. Schildkraut, the ultimate focus of any Section 2 inquiry will continue to be what it has been for decades: whether and to what degree consumers are hurt by a company's behavior.

WSJ: Sherman Stirs: U.S. Revives Section 2 of the Antitrust Act

According to Marc Schildkraut, an antitrust lawyer at Howery LLP, Justice Department lawyers in the previous administration used a test that weighed whether the anticompetitive effects of behavior disproportionately outweighed any good that such behavior might bring consumers.

WSJ: Sherman Stirs: U.S. Revives Section 2 of the Antitrust Act