British spies can help themselves to data collected by the NSA from the telephone calls and Internet communications of Americans without a warrant, a new court document shows. The agreement between the NSA and its British equivalent, Government Communications Headquarters (GCHQ) means that American citizen's data can be seen and stored by the United States' closest ally without a warrant when that is 'not technically feasible'. Anything discovered in the data, once obtained, can be kept by the British for up to two years and specifically relates to 'unselected' or raw data. But, this deadline can be extended unilaterally by 'senior UK officials' if they believe it to be necessary for national security purposes.
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Britain's Government Communications Headquarters (GCHQ)  privileged agreement with National Security Agency revealed
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Allowed to obtain raw data from American emails and telephone calls without a warrant
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Revelation exposed during legal challenge in the UK brought by civil rights groups
@placeholder lawmakers briefed by the agency have assured the public that a warrant was in place "in each case where GCHQ sought information from the U.S."