The National Security Agency's broad collection of U.S. phone customer data received its first significant legal challenge since the disclosure of the program last week.

The American Civil Liberties Union filed a lawsuit in federal court Tuesday, alleging that the National Security Agency was violating the ACLU's constitutional rights. The ACLU said it is a customer of Verizon Communications Inc.'s Verizon Business Network Services and it said metadata from the ACLU's phone calls are being collected.

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