On the surface, it may appear that Google has not violated antitrust law, Pociask added. "But there are real anticompetitive risks," he said. "Not from the operating system per se as much as it is from the whole online dominance we're seeing."
Other antitrust experts disagreed, saying Google's entrance into the OS market would benefit consumers by creating a legitimate competitor to Microsoft's Windows.
Google has recently faced other antitrust probes, with the U.S. Department of Justice looking into its digital book settlement with publishers, and ties between the Google and Apple boards. The DOJ has also opposed an advertising deal with rival Yahoo. But Google's entrance into the OS market is the "opposite of something raising antitrust concerns," said Evan Stewart, a partner with the Zuckerman Spaeder law firm. "This looks like extremely healthy, competitive, consumer-benefiting innovation."
"More competition in the operating system market has got to be viewed as a good thing," said Keith Hylton, a professor at the Boston University School of Law.
If anything, Google's move may give Microsoft an argument before antitrust regulators in Europe and the Far East that there is strong competition for OSes, Hylton said. However, it also raises questions about whether Google acted fairly when it complained to antitrust authorities in recent years about some Microsoft OS decisions, and when it worked to prevent Microsoft from acquiring Yahoo, he said.
"All that stuff looks a little bit stranger now that Google has entered the operating system market," he said. "Now it looks like the classic business of fending off rivals from your own markets when you're trying to enter theirs. I guess that's taking advantage of everything you can, but that doesn't appear to be honorable behavior."
Note: This story was amended on July 9, 2009.