The NSA will stop collecting U.S. phone data. Now what?

After a bitter congressional battle, President Obama has signed legislation to phase out the National Security Agency’s vast collection of U.S. telephone records, a historic rollback of government surveillance powers.

Here’s what you need to know:

What happens now?

The NSA can continue collecting Americans’ phone records for the next six months. The system was switched off late Sunday after the Senate failed to extend the law used to authorize it. Intelligence officials say it will take another day or so for the data pipelines to reopen, but NSA computers then will vacuum up data from any calls placed or received while the system was down.

What happens then?

Starting Nov. 29, the nation’s telephone companies will be expected to store toll records themselves and to format them for potential searches. They will receive government money and technical specifications to comply with the requirements. To access the so-called metadata -- the numbers called and the length and time of each call, but not the contents -- the government will need to obtain approval from the Foreign Intelligence Surveillance Court on a case-by-case basis, and only in terrorism and espionage investigations.

Will the NSA erase its archive of phone data?

No. The NSA won’t delete the database from government servers. They will try to protect it with software designed to set off alarms if anyone tries to illegally access the data.

Will the change increase the risk of terrorism?

Depends on whom you ask. Some in the Senate insisted the shift puts the nation at greater risk. Others argued that the NSA program hasn’t stopped a single terrorism plot. Intelligence officials have searched the NSA database about 300 times each year, and say the results have been useful in finding links between potential suspects in terrorism and espionage investigations.

Can phone companies refuse NSA requests?

No, although some may try. NSA will need an order from the Foreign Intelligence Surveillance Court each time it wants to access records held by telecommunication companies. If companies refuse, they could be in violation of a court order. Some companies that sell unlimited calling plans have argued that they don’t keep toll data on customers’ calls. Intelligence officials are concerned that some companies may try to opt out so they can advertise that they don’t provide data to U.S. spy agencies.

Do intelligence officials support the changes?

Yes. Director of National Intelligence James R. Clapper and Atty. Gen. Loretta Lynch told House leaders last month that the USA Freedom Act “preserves the essential operational capabilities” of the NSA program.

Is six months enough time to make the switch?

The NSA says yes. Some Senate Republicans tried to amend the House-passed bill to extend the transition period to one year. They also wanted require phone companies to notify the government if they hold data for a shorter period than the 18 months required under current rules. Those efforts failed and the USA Freedom Act passed the Senate unchanged in a 67-32 vote Tuesday night.

Did other authorities expire on Sunday?

Yes, three other provisions in the Patriot Act expired. But they were all reinstated in the law passed Tuesday. One provision makes it easier for the FBI to collect business records, such as credit card and banking data, in terrorism cases. Another authorizes “roving wiretaps” that permit the FBI to eavesdrop on every phone used by a terrorism suspect without obtaining a warrant for each device. The third lets the FBI seek a court order to wiretap a terrorism suspect who isn’t linked to a specific group.

What else does the USA Freedom Act do?

The bill creates a panel of independent advocates for privacy and civil liberties to argue before the Foreign Intelligence Surveillance Court for the first time. The court now hears only from government lawyers. The bill also requires the court make public significant legal rulings. In addition, it allows companies and individuals, for the first time, to challenge the gag orders that routinely come with data demands from the government under so-called national security letters.

Why is this happening now?

The NSA began collecting domestic phone data in secret after the Sept. 11 terrorist attacks. The Foreign Intelligence Surveillance Court specifically authorized the program five years later, in 2006, after amendments to the Patriot Act were signed into law. The program came to light in June 2013 when NSA contractor Edward Snowden leaked classified documents to news organizations about NSA surveillance programs around the world. The Justice Department charged Snowden, who fled and now lives in Russia, with espionage and other crimes. But the public outcry about domestic surveillance forced Congress to scale back the program in the most significant retrenchment of government spying powers since the 1970s. The new law also marks the only legislative reform to result from the Snowden leaks.

Twitter: @ByBrianBennett