Twitter released a report on Monday about the user information requests it has received from governments this year and how it responded to them.
The data shows that the U.S. government asked for information on far more users than any other country. Between Jan. 1 and June 30, Twitter received 679 requests for information from American authorities pertaining to 948 users.
Japan came in a distant second, with 98 information requests concerning 147 users.
Most Twitter users are in the United States, according to data published in January by Semiocast. Japan has the third-largest user base, after Brazil. Twitter noted that some requests may have targeted the same users or nonexistent users.
Twitter provided all or part of the information requested in 75 percent of the cases initiated by the U.S. government. It provided information in response to half the requests from the Netherlands and a third of the requests from Japan and Australia.
Most requests were in connection with criminal investigations or cases, Twitter said. The number of requests in 2012 has already exceeded the total for all of 2011, it said.
That's likely because governments are increasingly catching on that social networks store a great deal of information about their users that could be useful to law enforcement, said Eva Galperin, international freedom of expression coordinator at the Electronic Frontier Foundation. The information sometimes includes physical location and political and social affiliations.
"It's really up to the companies to decide whether or not they're going to comply with requests for information, so they become these extremely powerful arbiters that are capable of de facto censorship," Galperin said.
The EFF gives Twitter higher marks than some other companies when it comes to being transparent about government requests and sticking up for its users in court. For instance, in a current case, it has resisted [PDF] handing over its data on an Occupy Wall Street protester.
Protecting user privacy can be a good business strategy, according to Chris Conley, a technology and civil liberties attorney at the American Civil Liberties Union of Northern California.
Twitter "recognizes that users use Twitter not just because it's a great service, but also because they trust the company," he said.
"The more you can show users that you're trustworthy by doing whatever you can to protect their information, the more likely they are to continue to rely on and engage with your service," Conley said.
Google issues a similar report periodically, and has also said that the most requests originate from the U.S.
Cameron Scott covers search, web services and privacy for The IDG News Service. Follow Cameron on Twitter at CScott_IDG.