At Tuesday's hearing, officials detailed how the programs operate and the judicial and legislative oversight involved, repeating several times how access to the content of e-mails or telephone calls -- or even the names of people involved -- required authorization.
Deputy Attorney General James Cole noted that basic phone records collected under Section 215 of the Patriot Act were not protected by Fourth Amendment rights to privacy, citing a 1979 Supreme Court ruling.
In the case, Smith v. Maryland, the justices ruled that information about telephone calls -- such as their time and duration -- was different from the content of the calls and therefore not protected under the Fourth Amendment.
Cole also provided a detailed description of the legal framework of the programs, noting that the anti-terrorism surveillance effort is not "off the books" or "hidden away."
"This is part of what government puts together and discusses," he said. "Statutes are passed. It is overseen by three branches of our government -- the Legislature, the Judiciary, and the Executive Branch."
He described the U.S. phone records collected under Section 215 as basic information "just like what you would get in your own phone bill."
"It is the number that was dialed from, the number that was dialed to, the date and the length of time. That's all we get," he said. "We do not get the identity of any of the parties to this phone call. We don't get any cell site or location information as to where any of these phones were located. And, most importantly, and you're probably going to hear this about 100 times today, we don't get any content under this. We don't listen in on anybody's calls under this program at all."
Instead, it takes permission from a special court to get access to further information, based on a verifiable link to a terrorism investigation, Cole explained. Such links have mostly come from another surveillance program that collects communications information of foreign terrorism suspects living overseas.
Critics question the need to store the vast amount of U.S. phone records, saying it creates a database prone to abuses and provides little return for the risk and privacy concerns.
Alexander said Tuesday the phone database played a role in stopping 10 terrorist acts since the 9/11 attacks. At the same time, he and other officials said there were no cases they knew of in which anyone willfully misused the system to access information.
"If you're looking for the needle in a haystack," Cole said, "you have to have the haystack."