WASHINGTON — For the first time since the aftermath of the terrorist attacks of Sept. 11, 2001, Americans are again free to place phone calls — to friends, lovers, business associates, political groups, doctors and pizza restaurants — without having logs of those contacts vacuumed up in bulk by the National Security Agency.

And for the first time in nearly 14 years, if government agents identify new phone numbers that they suspect are linked to terrorism, they will have to subpoena phone companies for associated calling records and wait for the response to see if anyone in the United States has been in contact with that number. The N.S.A. can no longer simply query its database for the information.

This unusual situation may last only a few days, until Congress can reach an accommodation over three counterterrorism laws that expired at 12:01 a.m. Monday.

Nonetheless, the fact that Congress allowed the laws to lapse — the most important of them is the purported legal basis for the bulk records collection program — is an extraordinary moment in the story of the tensions between post-9/11 policies and privacy rights. It has led to heated warnings in the political realm about exposing the country to heightened risk of attack.