Tech companies seek limits on government surveillance

Some U.S. technology giants are asking the Obama administration and Congress to rein in government surveillance.

Facebook, Apple, Twitter, Google and Microsoft are among the companies signing an open letter arguing that surveillance has gone too far. The companies say they're improving encryption and fighting to limit surveillance requests, but they're also asking for new legal changes to limit surveillance.

This comes after recent revelations from documents leaked by former National Security Agency contractor Edward Snowden. His leaks have lifted the veil on the agency's vast surveillance databases, many of...