Balancing liberty and security is tough. We're about to find out whether we struck the right balance. Congress recently considered the extension of various intelligence collection authorities set to expire under the USA PATRIOT Act, in the end voting for new restrictions. This, along with the most recent reporting of expanded government surveillance in order to identify hackers, has renewed the debate of the appropriate balance between security and liberty.

One of the more controversial PATRIOT Act provisions targeted by civil libertarians is the bulk collection by the National Security Agency of meta data in the possession of third parties. Although the collection of meta data does not include the content of communication, critics claim this collection is unconstitutional and a violation of privacy rights. After, a 6-month transition period the data will be left in the hands of communications companies.

Throughout our history we have witnessed a shifting emphasis between our security and liberty depending on the threat to the United States. It is not surprising that after the Sept. 11 attacks, the U.S. government, with the support of a great majority of the American people, focused first on doing all that was necessary, as well as constitutional, to protect our security.

Admittedly, the Bush administration took extraordinary measures to collect information, but we did so in the face of an extraordinary threat to our security. Based on advice from administration lawyers that such measures were constitutional, and with the knowledge, if not the full support of key congressional leaders, our government collected information we believed necessary to protect America.

However, we did not ignore the liberty side of the equation. Mindful of the extraordinary power being exercised, the NSA imposed minimization procedures to guard against the inadvertent collection of substantive information of innocent Americans. The general counsel and inspector general at the NSA were charged with providing heightened guidance to operators in order to protect against mistakes and abuse. There were routine training sessions and periodic evaluations and to ensure NSA operations remained within authorized limits. Finally,key congressional members were briefed repeatedly about our collection efforts.

Since the 9-11 attacks, the nature of America's threats have changed. Due in part to organizational restructuring within our federal and state governments, as well as better communication, coordination and consultation between federal, state and local authorities, we have avoided another attack of the scale we witnessed on Sept. 11. The facts, supported by congressional testimony under oath by experts in the intelligence community, is that the measures taken by the Bush administration (many of which have continued under the Obama administration) were necessary against the known threats and they were effective in protecting America.

With the passage of time and an evolving threat environment, the government has a responsibility to reconsider the appropriate balance today between security and liberty. However, it should be based on facts — not political or campaign rhetoric. It should also be based on the law. For example, the U.S. Supreme Court has held that the acquisition of personal information like telephone numbers already in the possession of third parties such as telecom carriers does not implicate the Fourth Amendment because there is no reasonable expectation of privacy in such information under our Constitution.

Nor, as some have suggested, is a warrantless search necessarily illegal. The Fourth Amendment prohibits unreasonable searches and seizures. In the criminal context, the Fourth Amendment reasonableness requirement usually requires a showing of probable cause and a warrant. However, the Supreme Court repeatedly has held that in situations involving "special needs" that go beyond a routine interest in law enforcement, the warrant requirement is sometimes inapplicable. Foreign intelligence collection, especially in the midst of a conflict in which the enemy has already attacked the United States, fits comfortably in my judgment within the area of special needs where the Fourth Amendment's touchstone of reasonableness can be satisfied under the right circumstances without resort to a warrant.

Last week the president signed into law the USA Freedom Act, a law that continues several of the authorities under the PATRIOT Act, but curtails other key aspects including the government's ability to access bulk collection of metadata from third parties. Privacy advocates hail the law as a win for privacy, but it remains to be seen whether it truly is a win for America.

ISIL is on the move around the world. Seemingly every week there is a reported story of a takedown of an ISIL disciple within our borders, chilling reminders of the evolving threat. Without access to the classified threat matrix or an appreciation of the strength of our intelligence capabilities, it is difficult for the American people to judge whether this new law strikes the appropriate balance between security and liberty. What we do know is that because of the USA Freedom Act, it is now more difficult for the government to gather certain kinds of information. If we must win the war for information in order to win the war against extremists, then we have to question whether Congress and the president achieved the right balance. Only time will tell.

Alberto R. Gonzales is the former U.S. attorney general and White House counsel in the George W. Bush Administration. He is dean of Belmont University College of Law.