Google's absolute dominance in search has been under a great deal of scrutiny in Europe for some time now, but now it looks like the controversy is coming home: Senators Herb Kohl (D-Wis.) and Mike Lee (R-Utah) are asking the Federal Trade Commission to open an antitrust investigation into how Google uses search to promote its other products. Senator Kohl is the chairman of the Senate subcommittee on antitrust and competition and Senator Lee is the ranking member; the two led a particularly harsh hearing on Google's practices in September during which Eric Schmidt insisted Google didn't "cook" its results.

The questions raised in the letter are the same as outlined in that hearing: the senators are worried that Google has strong incentive to bias its search results to favor its own offerings, and quote a now-infamous 2007 speech by Google VP Marissa Mayer in which she said Google Maps and Finance links come first on search pages because "it seems only fair." The senators are also concerned that consumers don't know that Google's promoted links aren't part of the results hierarchy, and want the FTC to require Google to label those links accordingly.

Of course, for now it's just a letter, but these questions about how Google uses its search marketshare to drive adoption of its other products have been persistent and pernicious — we'll see if the FTC decides to finally act, and if Google decides to fight the seemingly inevitable or simply participate in order to clear the air.