Microsoft does not charge for government surveillance of its users, whereas Google charges $25 per user, according to a US Drug Enforcement Admission document turned up by security and privacy guru Christopher Soghoian.

With a Freedom of Information Act (FOIA) request, Soghoian has exposed four years of DEA spending on wiretaps and pen registers. A wiretap grabs actual telephone or Internet conversations, whereas a pen register merely grabs numbers and addresses that show who's doing the communicating.

In 2010, the document shows, the DEA paid ISPs, telcos, and other communication providers $6.7 million for pen registers and $6.5 million for wiretaps. Pen register payments more than tripled over the past three years and nearly doubled over the past two. Wiretap payments stayed roughly the same.

The documents confirm that Microsoft does not charge for surveillance. "There are no current costs for information requested with subpoenas, search warrants, pen registers, or Title II collection [wiretaps] for Microsoft Corporation," they say. But they show that Google charges $25 and Yahoo! $29.

As Soghoain points out, Google and Yahoo! may make more money from surveillance than they get directly from their email users. Basic Google and Yahoo! email accounts are free. Department of Justice documents (PDF) show that telcos may charge as much as $2,000 for a pen register.

On the one hand, Microsoft could be commended for choosing not to make a single penny from government surveillance. But on the other, Soghoian says, the company should at least charge that penny, as that would create a paper trail. "You don't like companies to make money spying on their customers, they should charge something," Soghoian tells us. "You can't FOIA Microsoft's invoices, because they don't send any invoices."

Most wiretap orders in the US involve narcotics cases, so DEA spending likely accounts for a majority of wiretap spending. ®