Which begs the question: Has the agency's effectiveness been blunted by the constant attacks and public perception, fair or not, that the agency is violating the privacy of ordinary Americans?
The NSA, queried by United Press International, deflected the question to the Office of the Director of National Intelligence, which supports the efforts of James Clapper, director of national intelligence in Washington.
Clapper's office didn't respond to a separate inquiry, but some commentators are showing concern.
In an op-ed in the Washington Post Jan. 3, Steven G. Bradbury, chief of the U.S, Justice Department's Office of Legal Counsel from 2005 to 2009, warned of the practical and motivational effects of the assault on the agency.
"If the integrity of the [NSA's] metadata program is put at risk and the NSA's ability to perform its mission significantly hampered, [leaker] Edward Snowden would realize his objectives," Bradbury wrote. "America's vital advantage in communications intelligence would be further degraded, and the dedicated men and women who carry out our intelligence programs would have an even deeper crisis of confidence."
Bradbury was a principal in the effort to get initial court approval for the NSA's collection of telephone metadata. His commentary was republished in the U.S. military newspaper Stars and Stripes.
The FBI, of course, is the point agency in the field to counter terror, which the NSA can't do. The FBI set up an operations center only miles from MetLife Stadium and the Super Bowl. As an intelligence agency itself, the FBI gathers its own information, even from its legates in U.S. embassies all over the world.
But the FBI doesn't even try to match the NSA's electronic global reach, and relies on it for information to head off domestic terror threats.
The critical report released Jan. 23 by the Privacy and Civil Liberties Oversight Board poses a huge political problem for the NSA, based at Fort Meade, Md., but with facilities elsewhere. The report says the NSA surveillance program is not supported by law, and in fact violates the Electronic Communications Privacy Act of 1986. The report says the program has constitutional problems as well.
In the report, the board concluded "the NSA's [metadata] program violates the Electronic Communications Privacy Act. That statute prohibits telephone companies from sharing customer records with the government except in response to specific enumerated circumstances -- which do not include orders issued under Section 215" of the Patriot Act.
"The closest analogue to the power conferred by Section 215 is the administrative subpoena," the board report said. "Indeed, Congress crafted Section 215 as a substitute for the administrative subpoena authority sought by the administration after the 9/11 attacks. ... An administrative agency may conduct an investigation [under Section 215 authority] even though it lacks probable cause to believe that any particular statute is being violated."
The five-member board, established in its initial form by Congress in 2004 as an independent executive branch entity, provided NSA critics with plenty of ammunition, but unlike a judge's opinion its conclusions and recommendations have no force of law.
News accounts of the board's report placed little stress on how it repeatedly said NSA employees had not abused the surveillance programs.
"Our nation is protected by men and women devoted to the rule of law," the report said. "In talking to dozens of career employees throughout the intelligence agencies, we found widespread dedication to the Constitution and eagerness to comply with whatever rules are laid down by Congress and the judiciary. We are grateful to the employees of the intelligence community for their cooperation with this study, and for working tirelessly to keep us safe. None of the comments in this report should be read in any way as a criticism of their integrity."
The board said it and the intelligence community had a "shared mission of protecting America from terrorism while also preserving 'the precious liberties that are vital to our way of life.'"
The report said it disagreed with the Bush and Obama administrations and with the 15 judges on the secret Foreign Intelligence Surveillance Act court that NSA collection of metadata from telephone records is underpinned by law.
"Since 2006, the government has argued before the [special Foreign Intelligence Surveillance Act] court that Section 215 of the Patriot Act provides a legal basis for the NSA's bulk telephone records program. The FISA court has agreed and has authorized the program."
But the review board said, "Having independently examined this statutory question, the board disagrees with the conclusions of the government and the FISA court."
The board said it found "there are multiple and cumulative reasons for concluding that Section 215 does not authorize the NSA's ongoing daily collection of telephone calling records concerning virtually every American."
The board also said it "concludes that Section 215 does not provide an adequate legal basis to support this program. Because the program is not statutorily authorized, it must be ended."
The NSA conducts two huge surveillance programs.
"Under one, the NSA collects telephone call records or metadata -- but not the content of phone conversations -- covering the calls of most Americans on an ongoing basis, subject to renewed approvals by the Foreign Intelligence Surveillance Court [the FISC hears rare government appeals from the FISA court].
"This program was approved by the FISC pursuant to Section 215. ...
"Under the second program, the government collects the content of electronic communications, including phone calls and emails, where the targets are reasonably believed to be non-U.S. persons located outside the United States. Section 702 of the FISA Amendments Act is the basis for this program."
Besides statutory problems, the board report found considerable constitutional problems. The Fourth Amendment bans "unreasonable" searches and seizures.
Analysis of the "NSA's telephone records program under the Fourth Amendment must begin by asking whether the agency's collection of calling records qualifies as a 'search' within the meaning of the amendment," the report said. "If not, as the government has argued in defense of the program, the Fourth Amendment and its restrictions do not apply to the NSA's activity."
The report conceded the "Supreme Court has ruled that the Fourth Amendment does not provide individuals with a right of privacy in the numbers that they dial from their telephones. More broadly, the court has concluded, any information that a person voluntarily discloses to a business or other entity loses all Fourth Amendment protection. This rule, referred to as the 'third-party doctrine,' means when government agents obtain records about a person that are held by a telephone company, bank or other institution, that does not qualify as a search under the Constitution.
"Although the Section 215 program encompasses much more information than the telephone numbers that a person dials, all of the information that the NSA collects under the program has been disclosed to telephone companies by their customers. Therefore, under the broad reading of the third-party doctrine widely adopted in the federal courts, none of the information is constitutionally protected, and the NSA may collect it without seeking a warrant or ensuring that its behavior satisfies the Fourth Amendment's standard of reasonableness."
The board echoed a federal judge in Washington who ruled against the constitutionality of the NSA metadata collection -- saying the U.S. Supreme Court may eventually come to re-examine the third-party doctrine in light of technology developments "that have become commonplace features of contemporary life."
Citing the First Amendment's guarantee of freedom of association, the board said: "Although the program is supported by a compelling government interest in combating terrorism, which can justify some intrusions on First Amendment rights, it is not narrowly tailored.
"The extraordinary breadth of this collection program creates a chilling effect on the First Amendment rights of Americans."
The record on the constitutionality of NSA metadata collection in federal court has been mixed.
In December, U.S. District Judge Richard Leon in Washington issued a preliminary injunction blocking the massive collection of phone records, which is conducted without a warrant, but stayed the injunction pending a government appeal.
Leon, a George W. Bush appointee, said a suit by Larry Klayman, the founder of Freedom Watch, has "demonstrated a substantial likelihood of success" on the basis of Fourth Amendment.
Though Leon granted Klayman's request for a preliminary injunction, he stayed his order pending an appeal by the Obama administration because of the "significant national security interests at stake in this case and the novelty of the constitutional issues."
Leon's ruling caused quite a stir in Washington, but it conflicts with the U.S. Supreme Court's ruling in Smith vs. Maryland. Leon dismissed Smith as out of step with modern reality.
In the 1979 Smith case, a Supreme Court said the installation of a "pen register" was not a search within the meaning of the Fourth Amendment, and did not require a warrant. A "pen register" collects the numbers called from a phone on an individual basis -- much like the metadata collection program does on a mass basis.
Later in December, U.S. District Judge William Pauley in New York dismissed the American Civil Liberties Union's constitutional challenge to the NSA program.
The judge said the program was a "blunt tool that only works because it collects everything."
Pauley, a Bill Clinton appointee, took a position in direct opposition to Leon's opinion.
"The privacy concerns at stake in Smith were far more individualized than those raised by the ACLU," Pauley wrote in his Dec. 17 opinion. And, "the business records created by Verizon are not 'plaintiffs' call records.' Those records are created and maintained by the telecommunications provider, not the ACLU. Under the Constitution, that distinction is critical because when a person voluntarily conveys information to a third party, he forfeits his right to privacy in the information."
Despite the ACLU argument, "the Supreme Court did not overrule Smith," Pauley said. "And the Supreme Court has instructed lower courts not to predict whether it would overrule a precedent even if its reasoning has been supplanted by later cases. ... Clear precedent applies because Smith held that a subscriber has no legitimate expectation of privacy in telephony metadata created by third parties. ... Inferior courts are bound by that precedent."
At the beginning of his 53-page opinion, Pauley cited the Sept. 11, 2001, terror attacks.
"While Americans depended on technology for the conveniences of modernity, al-Qaida plotted in a seventh-century milieu to use that technology against us," Pauley said. "It was a bold jujitsu. And it succeeded because conventional intelligence gathering could not detect diffuse filaments connecting al-Qaida."
Prior to those terror attacks, the NSA intercepted seven calls by eventual hijacker Khalid al-Mihdhar, who was living in San Diego. The calls went to an al-Qaida safe house in Yemen.
Though the calls were intercepted, the NSA could not capture the man's telephone number identifier.
"Without that identifier, NSA analysts concluded mistakenly that al-Mihdhar was overseas and not in the United States," Pauley wrote. "Telephony metadata would have furnished the missing information and might have permitted the NSA to notify the [FBI] of the fact that al-Mihdhar was calling the Yemeni safe house from inside the United States.
"The government learned from its mistake and adapted to confront a new enemy: a terror network capable of orchestrating attacks across the world," Pauley said. "It launched a number of countermeasures, including a bulk telephony metadata collection program -- a wide net that could find and isolate gossamer contacts among suspected terrorists in an ocean of seemingly disconnected data."
The judge cited several instances in which a "nascent plot" was headed off by NSA metadata information sent to the FBI, including planned attacks on the New York subway system and the New York Stock Exchange.
NSA leaker "Edward Snowden's unauthorized disclosure of Foreign Intelligence Surveillance Court orders has provoked a public debate and this litigation," Pauley said. "While robust discussions are under way across the nation, in Congress and the White House, the question for this court is whether the government's bulk telephony program is lawful. This court finds it is. But the question of whether that program should be conducted is for the other two coordinate branches of government" -- Congress and the Obama administration -- "to decide."
Down the road, the U.S. Supreme Court likely will have to decide which view prevails legally -- the review board's finding that the NSA programs are illegal and possibly unconstitutional, or the the argument from successive administrations and rulings from the FISA court that they are both legal and constitutional.
If the NSA's efforts head off a major terror attack in the United States or, in cooperation with Russia promised by President Obama, head off an attack in Sochi where thousands of Americans are gathering for the Games, it could sway public opinion. But it's unlikely the public would even know about it. The agency's activities are normally so secret that for decades a rather lame joke in Washington was that "NSA" stood for "No Such Agency."
However, one factor to consider in the court fight over NSA programs: Chief Justice John Roberts appoints the 15 judges on the FISA court, without oversight from Congress or the White House, and the judges presumably reflect his views.