The legal authority for US spy agencies' collection of Americans' phone records and other data expired at midnight on Sunday after the US Senate failed to pass legislation extending the powers.
After debate pitting Americans' distrust of intrusive government against fears of terrorist attacks, the Senate voted to advance reform legislation that would replace the bulk phone records program revealed two years ago by former National Security Agency contractor Edward Snowden.
Although the Senate did not act in time to keep the program from expiring, the vote was at least a partial victory for Democratic President Barack Obama, who had pushed for the reform measure as a compromise addressing privacy concerns while preserving a tool to help protect the country from attack.
But final Senate passage was delayed until at least Tuesday by objections from Senator Rand Paul, a libertarian Republican presidential hopeful who has fulminated against the NSA program as illegal and unconstitutional.
As a result, the government's collection and search of phone records terminated at midnight when key provisions of a post-Sept. 11, 2001, law known as the USA Patriot Act expired.