Web Firms' Data Proves Irresistible to Law Enforcers

Google does voluntarily publish a transparency report every six months in which it details the number of requests it receives from governments around the world to remove content from its services or hand over user data. But the numbers do not reveal how many users are affected by each request - only trends country by country.

Some governments are requiring internet companies to collect more data and keep it for longer, said Katarzyna Szymielewicz, executive director of Poland's Panoptykon Foundation, which campaigns for human rights in light of modern surveillance.

"Government agencies throughout the world are pushing companies to collect even more data than is needed for their business purposes," she told the conference.

"For example, we have a very controversial data retention regime which is currently under review. This requires people to store data for a period up to two years so it can easily be accessed by law enforcement agencies."

The ease and cost of surveillance are at an all-time low, Soghoian said, with Google charging an administrative fee of $US25 to hand over data, Yahoo charging $US20, and Microsoft and Facebook providing data for free.

"Now, one police officer from the comfort of their desk can track 20, 30, 50 people all through web interfaces provided by mobile companies and cloud computing companies," he said.

"The marginal cost of surveilling one more person is now essentially approaching zero."