Republican US Senator Rand Paul, along with a conservative political group, has filed a lawsuit against President Barack Obama and top US intelligence officials over alleged National Security Agency's (NSA) user telephone records gathering of millions of US citizens.
Arguing the programme breaches privacy rights protected by the US Constitution, the lawsuit sought a federal judge to stop the collection of the user data and destruction of the already gathered records.
Filing the lawsuit with FreedomWorks president Matt Kibbe, Paul seeks the lawsuit to be turned into a class action case for every US citizen who used a telephone in the past five years, and would then move to the US Supreme Court.
"We will ask the question in court whether a single warrant can apply to the records of every American phone user all the time, without limits, without individualisation," Paul said.
"We believe that this lawsuit could conceivably represent hundreds of millions of people who have phones lines in this country or cellphones.
"We think it may well be the largest class action lawsuit ever filed on behalf of the bill of rights."
Matt Kibbe said, "We think the government has overstepped its bounds, we think that the Fourth Amendment is something worth fighting for, and I think a lot of Americans agree with us."
Last month, a privacy watchdog dubbed Privacy and Civil Liberties Oversight Board (PCLOB) has ruled that NSA's mass collection of citizens' telephone data is illegal and a violation of civil liberties, with further demands to be shut down.