The past eight years have seen Washington take a back seat on antitrust issues and allowed Brussels to cement its place as the global competition capital as European regulators took on US companies such as Microsoft and Intel for alleged abuses.

Dropping Bush administration barriers to antitrust cases, Christine Varney, the new head of the Department of Justice’s antitrust division, on Monday signalled a return to the more interventionist approach of President Bill Clinton’s administration. But that does not mean a blow to business. Sean Heather, a lawyer at the US Chamber of Commerce, the largest US business group, said he was against “inappropriate” antitrust action but saw no reason to believe Ms Varney would pursue a “radical” agenda.