USA Freedom Act

Under the USA Freedom Act, the NSA can no longer collect phone call metadata without a court order. Metadata remain with private phone carriers but can be subpoenaed by the government.

The Senate voted Tuesday to advance a House-passed bill that would end the National Security Agency's bulk collection program. Edward Snowden also spoke via videolink to a conference in London.

Unable to overcome parliamentary maneuvers by Sen. Rand Paul, the Senate adjourned and let three provisions of the Patriot Act expire at midnight.

Three key provisions of the act sunset on June 1. The Senate has scheduled a rare Sunday session to try to pass a House measure that modifies some of the provisions.

If you haven't been paying attention, here's a primer on the changes Congress is considering making to U.S. surveillance practices.

The USA Freedom Act would extend many parts of the surveillance legislation while also barring the NSA's massive collection of Americans' phone data. The measure's fate in the Senate is uncertain.