If NSA surveillance program ends, phone record trove will endure

The National Security Agency will mothball its mammoth archive of Americans' telephone records, isolating the computer servers where they are stored and blocking investigators' access, but will not destroy the database if its legal authority to collect the material expires on schedule. The NSA's determination to keep billions of domestic toll records for counter-terrorism and espionage investigations adds another note of uncertainty to a debate that pits the Obama administration's national security team against opponents who argue the government data trove violates Americans' privacy and civil liberties.

The political and legal dispute will come to a head May 31 when the Republican-led Senate returns to work a day early to seek a resolution — hours before the law used to authorize the controversial NSA program, and several other key counter-terrorism provisions, expires at 11:59 p.m. The final eight hours — starting at 3:59 p.m. Sunday — will see a flurry of activity at U.S. phone companies and at the NSA as engineers take down servers, reconfigure monitoring software and unplug hardware from the main pipeline of telephone data traffic, according to several senior administration officials. If the Senate stalemate pushes past 7:59 p.m., holes in the incoming data will begin to appear — and will grow — until nothing is collected after midnight, the officials said, speaking on condition of anonymity to discuss internal planning.