The news this week is full of speculation about how the affair between CIA director David Petraeus and his biographer, Paula Broadwell, was discovered. The revelation forced Petraeus' resignation on Friday. Press accounts have suggested that the FBI learned of the affair while digging through Broadwell's Gmail account.

Broadwell would be just one of thousands of Americans whose private communications Google has turned over to law enforcement officials this year, according to a new Google report. In recent years, Google has set the standard for transparency among major tech companies by releasing statistics twice a year about the volume of takedown and surveillance requests it receives (Twitter has recently started offering similar information as well). The latest batch of Google's statistics, covering the first half of 2012, is out this week. It shows that the volume of surveillance and takedown requests has continued to grow rapidly. The United States leads the pack in the volume of surveillance requests, while Turkey, Germany, the United Kingdom, and Brazil were all major sources of takedown requests.

Worldwide, 34,000 Google users were the subject of information requests by governments in the first half of 2012. That represents a 36 percent increase over the same period in 2011. Takedown requests grew at an even faster clip. Non-copyright takedown requests almost doubled, from 949 requests in the first half of 2011 to 1,791 in the first half of this year.

The volume of copyright-related takedowns, mostly from private organizations, grew fastest of all. Unlike the other categories, which are released every six months, Google releases copyright takedown statistics on a weekly basis. In mid-2011, Google was receiving takedown requests for approximately 100,000 URLs per week. Today, the search giant is getting requests for almost 2 million URLs every week:

These statistics suggest an escalating arms race between copyright holders and file sharing sites. A handful of organizations, including Fox Media, the Recording Industry Association of America and its UK counterpart the BPI, and dedicated takedown firms such as Degban and Takedown Piracy LLC, account for a significant fraction of these takedown requests. Degban is the world's leader, issuing 1.75 million takedowns related to 3,528 domains on behalf of 47 different copyright holders.

Surveillance and censorship around the world

The United States leads the pack in government surveillance requests. Law enforcement officials in the United States issued almost 8,000 requests for user information, and Google complied with the requests 90 percent of the time. For comparison, the next most active country is India. With four times the population of the United States, India submitted just 2,319 requests, and Google complied with only about two-thirds of those requests. Indeed, Ars Technica's calculations suggest that Google complied with fewer than 6,800 information requests from all countries other than the United States put together, compared with more than 7,100 successful requests by the United States.

The report includes detailed country-level anecdotes that give an interesting window into the friction between the global Internet and local laws. For example, Thailand has laws prohibiting insults to their king. Turkey has similar laws prohibiting insults to Atatürk, the George Washington of modern Turkey. During the first half of 2012, Google was asked to block videos insulting both figures. In both cases, Google complied by blocking locals from accessing some of the videos.

Google faced numerous requests around the world to remove materials critical of senior government officials. In many cases, the company refused to comply with these requests. Google says it refused to remove "a YouTube video of statements made against members of law enforcement" in Australia. Google also refused to remove videos and blog posts critical of public officials in Brazil, China, France, the Phillipines, the United Kingdom, and the United States.

Google did remove content that allegedly defamed a German politician's wife from search results. In the United States, the Mountain View firm removed 223 links to "websites that allegedly defame organizations and individuals" from its search results.

We'll close with the caveat we include every time we cover Google's transparency reports: while Google's statistics provide an informative peek into a world that is generally hidden from public view, they also provide an extremely incomplete picture of the volume of surveillance activity. Without comparable statistics from Google competitors such as Facebook and Microsoft, it's difficult to know the overall volume of surveillance. More importantly, much government surveillance doesn't target Web hosts at all. Major telecom carriers like AT&T and Verizon are also major targets, and as far as we know none of them have followed Google's good example and released surveillance statistics.

Google may also be legally barred from disclosing certain types of surveillance in the United States, so it's possible the statistics they have shared with us dramatically understate the scale of Google's participation in government surveillance. Google's report is a valuable source of information. But to get a comprehensive understanding of government surveillance, we really need governments themselves to collect and publish statistics on their own surveillance activities.

Update: A Google representative emailed us to offer one reason for the large number of US information requests: "government requests for user data from the US include those issued by US authorities on behalf of other governments due to mutual legal assistance treaties (MLAT) and other diplomatic mechanisms." Google wasn't able to give any details on what fraction of "United States" requests were made on behalf of foreign governments.