The Federal Trade Commission’s decision to open an investigation into potential anticompetitive or deceptive practices at Google is a welcome move. While the Internet company has been a leader in innovation, giving consumers exciting new choices online, the public’s interest lies in ensuring fair competition in this fast-changing arena.

There is no conclusive evidence that Google abuses its dominance in search by putting its own services, like YouTube, at the top of search results while shoving down competitors. Nonetheless, its aggressive expansion into new businesses, coupled with its ability to determine the all-important order of search results, warrants an increased level of scrutiny by regulators. Each new venture gives Google a new reason to use its tools to shut out rivals.

Take the company’s push into the smartphone market with its Android operating system. Skyhook Wireless, which provides location services to pinpoint the position of cellphone users, filed a suit late last year accusing Google of getting manufacturers like Motorola to break contracts with Skyhook and use Google location services on Android phones instead. It alleged Google made bogus claims that Skyhook’s system did not comply with Android specifications and that Google had threatened Motorola with denying it timely access to new versions of Android and other Google applications. Google declined to discuss the case but has called it “a baseless complaint” in court filings.

The F.T.C.’s investigation should look into Google’s behavior across all its businesses. Google’s argument that it must maintain the integrity of Android is plausible. So is its claim that it tweaks its search algorithm to improve the quality of its results — bumping down low-quality Web sites like link farms with no original content. Even favoring its own services, say delivering a Google map as a response to an address query, could serve consumers. The investigation will not necessarily lead to charges of misconduct. Google, however, is too important to most people’s Internet experience for regulators not to examine its behavior.