US spy agencies have lost legal authority to collect Americans' phone data in bulk, after the country's Senate failed to agree a deal.
The Patriot Act's relevant data collection provisions lapsed at midnight local time.
Republican Presidential hopeful Senator Rand Paul led efforts to block the extension of the Patriot Act, insisting its data collection powers are illegal and unconstitutional.
The US Senate did vote to move forward with the White House-supported Freedom Act, so new ways of collecting information are likely to be approved within days.
However, the Obama administration says the Senate has caused an 'irresponsible lapse'.
Republican Senate leader Mitch McConnell says opponents of the Patriot Act were being asked to approve only a short extension of limited elements of it.
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