Andrew McDiarmid, a policy analyst for the Center for Democracy and Technology, said voluntary efforts like Google's are preferable to legislation, but he argued the effectiveness of the measure depends on its implementation.
John Bergmayer, a lawyer for Public Knowledge, warned that "Google has set up a system that may be abused by bad faith actors who want to suppress their rivals and competitors" and urged the company to implement the system carefully.
"If Google's new policy helps users find legitimate sources of content, protects the valid interests of copyright holders, and doesn't penalize lawful sites, then it's a win all around," Bergmayer wrote. "But any new system such as this has potential dangers and unintended consequences, and can be abused. Google is undoubtedly aware of this — but it remains to be seen how it will respond to problems that arise, and whether it will continue to put the interests of users first."
Google is already under intense scrutiny from American and European regulators for antitrust concerns, and the penalty could cause more regulatory headaches for Google if it demotes its competitors' sites but not its own, like YouTube.
The Google spokesman said the company is sensitive to antitrust complaints. He explained Google's sites will also be covered by the penalty, although he doesn't expect them to be demoted.
The spokesman said the penalty is about more than just the raw calculation of piracy complaints, but he noted that the exact details of Google's search algorithm are a closely guarded secret.
Google could begin incorporating the piracy penalty into its search results as soon as this week.