In what must have seemed to some observers as a moment of brilliant irony, Microsoft at long last brought its case to the U.S. Senate, where it told legislators that Google's proposed DoubleClick acquisition would violate antitrust laws.

The Senate Judiciary subcommittee on antitrust heard from Microsoft General Counsel Brad Smith, who told lawmakers that Google was unfairly attempting to corner the online advertising industry. Smith also claimed that a merger would make consumers vulnerable to possible security breaches of private data.

While Microsoft touted privacy concerns, its position was somewhat undermined by testimony from Thomas Lenard, a senior fellow at the Progress and Freedom Foundation – an organization supported by both Microsoft and Google.

"The evidence is that the use of personal information by online advertisers produces substantial consumer benefits," Lenard said.

What seems more plausible to many observers is Microsoft's own designs on the interactive advertising industry, highlighted by its purchase of DoubleClick rival aQuantive in May. Microsoft has a slight edge there, having already closed its deal for aQuantive.

In the days leading up to the hearing, allegations have surfaced that Microsoft may have orchestrated a PR campaign to undermine Google's acquisition of DoubleClick by lobbying media outlets about the privacy implications of deal.

For all the legislative maneuvering and public relations efforts, Microsoft come out swinging in recent days, anointing aQuantive boss Brian McAndrews as its general in charge of battling Google for dominance in online advertising.