The secrecy surrounding government surveillance is a constant source of frustration to privacy activists and scholars: It’s hard to have a serious discussion about policy when it’s like pulling teeth to get the most elementary statistics about the scope of state information gathering, let alone any more detailed information. Even when reporting is statutorily required, government agencies tend to drag their heels making statistics available to Congress – and it can take even longer to make the information more widely accessible. Phone and Internet companies, even when they join the fight against excessive demands for information, are typically just as reluctant to talk publicly about just how much of their customers’ information they’re required to disclose. That’s why I’m so pleased at the news that Google has launched their Government Requests transparency tool.  It shows a global map on which users can see how many governmental demands for user information or content removal have been made to Google’s ever-growing empire of sites – now including Blogger, YouTube, and Gmail – starting with the last six months.

So far, the information up there is both somewhat limited and lacking context.  For instance, it might seem odd that Brazil tops the list of governmental information hounds until you bear in mind that Google’s Orkut social network, while little-used by Americans, is the Brazilian equivalent of Facebook.

There are also huge gaps in the data: The United States comes in second with 3,580 requests from law enforcement at all levels, but that doesn’t include intelligence requests, so National Security Letters (tens of thousands of which are issued every year) and FISA warrants or “metadata” orders (which dwarf ordinary federal wiretaps in number) aren’t part of the tally. And since China considers all such government information requests to be state secrets – whether for criminal or intelligence investigations – no data from the People’s Republic is included.

Neither is there any detail about the requests they have counted – how many are demands for basic subscriber information, how many for communications metadata, and how many for actual e-mail or chat contents. The data on censorship is similarly limited: They’re counting governmental but not civil requests, such as takedown notices under the Digital Millennium Copyright Act.

For all those limits – and the company will be striving to provide some more detail, within the limits of the law – this is a great step toward bringing vital transparency to the shadowy world of government surveillance, and some nourishment to the data-starved wretches who seek to study it. We cannot have a meaningful conversation about whether censorship or invasion of privacy in the name of security have gone too far if we do not know, at a minimum, what the government is doing. So, for a bit of perspective, we know that U.S. courts reported a combined total of 1,793 (criminal, not intel) wiretaps sought by both federal and state authorities. Almost none of these (less than 1 percent) were for electronic interception.

This may sound surprising, unless you keep in mind that federal law establishes a very high standard for the “live” interception of communications over a wire, but makes it substantially easier – under some circumstances rather terrifyingly easy – to get stored communications records. So there’s very little reason for police to jump through all the hoops imposed on wiretap orders when they want to read a target’s e-mails.

If and when Google were to break down that information about requests – to show how many were “full content” as opposed to metadata requests – we would begin to have a far more accurate picture of the true scope of governmental spying. Should other major players like Yahoo and Facebook be inspired to follow Google’s admirable lead here, it would be better still.  Already, though, that one data point from a single company – showing more than twice as many data requests as the total number of phone wiretaps reported for the entire country – suggests that there is vastly more actual surveillance going on than one might infer from official wiretap numbers.