At the center of the square off over the access to private personal data online -- a much publicized debate that extends from Beijing to Washington -- stands an uncertain arbiter: the search engine.

The companies that operate the most popular search engines -- Google, Yahoo and Microsoft -- are making decisions about how the information they collect about user behavior should be protected, in some cases from the eyes of governments that want to take a closer look but lack a clear legal right to do so.

"Search engines are the future of [that] debate," says Timothy Wu, a Columbia Law School professor specializing in telecommunications law, copyright, and international trade. "Questions about policy ultimately are going to be handled by search engines -- whether we live in a more or less government-controlled country."

As the collection and storage of data becomes an industry of its own, the availability of the information "is a temptation for the government," says Sherwin Siy, staff counsel at the Electronic Privacy Information Center, a nonprofit public interest group. He, Wu and others spoke Tuesday in a panel discussion at the Search Engine Strategies conference in New York City.

And when governments -- not just in the United States, but around the world -- want information about their citizens, "Search engines are first places they go," says Wu, who is also the co-author of a new book, "Who Controls the Internet."

Recently, Google has resisted a subpoena by the Justice Department to turn over search query data, while in China, Yahoo has complied with government requests for data that have led to the imprisonment of at least three people.

In the past year, search engines have unveiled new features in their services that are based on an individual's history of online inquiries. Google's Personalized Search, for example, still in beta after launching last June, orders results based on what a user has sought out in the past.

Searches conducted on a user-downloaded toolbar, offered by all the major U.S. portals, collect more information than a search engine normally would.

Ramez Naam, group program manager for Microsoft Corp.'s MSN Search, believes that consumers are not as concerned about the security of information related to their Internet searches as they are with fighting computer viruses, for which they often purchase extra software protection.

"Privacy is not something that people are saying this is priority one, you have to have this," he says. Anonymous surfing software is available from companies such as Anonymizer, but "few people are so motivated that they would install this."

Microsoft is working to make its privacy agreements more comprehensible for the average user, he says.

While Amazon.com has shown that personalization can be a valuable service for consumers when they're shopping, "in the search engine world we've not yet demonstrated this is a great feature."

"We're highly motivated to figure out what we can do to give people the privacy they need and the services on top of that," Naam says. "There's certainly an opportunity to provide value-add to customers and make more money."

A key public policy question for the future will be how easily search engines and future browser software accommodate individuals who wish to protect their identity while using the Internet, Wu says.

"Search engines can't help but take a political stance," he says. "When they make a decision to put an Anonymizer in software, they're making a decision."