The A.C.L.U. has frequently assisted other plaintiffs in challenges against national security policies, but the government has generally persuaded courts to dismiss such lawsuits without any ruling on the legal merits after arguing that litigation over any classified program would reveal state secrets or that the plaintiffs could not prove they were personally affected and so lacked standing to sue.

This case may be different. The government has now declassified the existence of the program on domestic call record “metadata.” And the A.C.L.U. itself is a customer of Verizon Business Network Services — the subsidiary of Verizon Communications that was the recipient of a secret court order for all its domestic calling records — which it says gives it direct standing to bring the lawsuit.

The call logging program is keeping a record of “metadata” from domestic phone calls, including which numbers were dialed and received, from which location, and the time and duration of the communication, officials have said.