After the Senate declined to reauthorize the bulk collection of phone records, the National Security Agency began shuttering its controversial counter-terrorism program over the weekend. The Senate failed to reach an agreement to extend the program beyond May 31, when the law used to authorize it will expire. Some intelligence and law enforcement officials have argued that the program is crucial to tracking terrorists. While the Senate rejected two bills that would have continued the program, some believe an agreement could still be reached before the deadline.

Officials initiated the complex process of shutting down the program now to stay within the bounds of the law.

“Intelligence officials warned of a precipitous gap in data collected if Congress does not come up with a plan before May 31 to either expand the NSA’s authority — which is unlikely — or replace the program in an orderly way over several months,” reports the Los Angeles Times.

“The start of the wind-down process marks the most significant step the Obama administration has taken to limit the data collection since former NSA contractor Edward Snowden leaked documents in 2013 showing the government was siphoning and holding millions of so-called toll records of domestic phone calls.”

Opponents of the program have expressed their concern that the database could allow future administrations to use the information in ways that would impact citizens’ privacy.

Intelligence officials began steps now to adhere to the law, “particularly after a federal circuit court ruling this month found the NSA program to be illegal,” notes the article. “The decision invalidated the legal analysis of the Patriot Act that NSA lawyers used for years to justify large-scale collection and storage of call records.”