Here is how we THINK this program works, based on several calls.

The National Security Agency, with approval from the Foreign Intelligence Surveillance Act court, goes to the phone companies and says: Every day, pump your data about phone calls into our big government tank -- only phone numbers (not names), along with other data about the calls, such as where they came from, how long they lasted, what numbers were dialed, and so on.

The government does this for two reasons. First, the phone companies themselves retain this data only for 30-90 days. Second, having this data aggregated in one place avoids the need, when checking out a specific number, to have to go get a court order for each phone company to track a specific number, when the government does not know what company handled that number.

(USA Today reported on this program back in 2006.)

So the order made public by the Guardian covers part one of this process. 

Part two, however, involves the authority to dive into the government's big tank of phone data to check out a specific number. It does this under protocols and internal controls that are approved in advance and must be reviewed by the FISA court periodically. This means that the tank can be accessed only for specific reasons -- not to generally roam through.

So, for example, when the police in London bust up a terror cell and find a U.S. number was on one of their cell phones, the U.S. government can then check that number against its big tank of phone data, without having to go to every carrier.

But there are several questions for the administration to answer, among them:

-- How does the FOREIGN intelligence surveillance court have authority to order the phone companies to turn over records of DOMESTIC calls, as well as international ones?

-- How does it satisfy the Fourth Amendment to require a company to turn over all its data in advance?

-- And what's the Fourth Amendment authority to tell a court what specific searches were conducted on that data after the fact, instead of in advance?

The United States Supreme Court has declined to take up the hottest question about gun rights now dividing the nation's courts: is there a constitutional right to carry a gun outside the home?

The justices today passed up a challenge brought by five residents of New York's Westchester County to a state law that forbids carrying a gun unless a person desiring to do so can show "proper cause" -- some special need for protection that goes beyond a general desire for self-defense. Those who can demonstrate that need can be granted a license to carry a firearm. The federal appeals courts are split on whether the Second Amendment provides a right to carry a gun in public.

Related - First Thoughts: Under the gun

In striking down an Illinois law that banned the concealed carrying of a gun, an appeals court in the Midwest said "the Second Amendment right to bear arms implies a right to carry a loaded gun outside the home." But other federal courts have gone in the opposite direction, upholding the New York law as well as one in Maryland that requires gun owners to show "a good and substantial reason" for carrying a handgun. California, Hawaii, Massachusetts, and New Jersey have similarly restrictive laws.

The Supreme Court's landmark decision on gun rights in 2008 declared that the Constitution provides an individual right to own a gun, not a right granted simply to organized militias.  But the ruling dealt only with the right to keep a gun at home for self defense. Though the court took a pass today on it today, the issue is bound to return, requiring the justices to consider whether that right applies outside the home as well and, if it does, how much state and local laws can restrict it.

Administration officials say the Justice Department will urge the U.S. Supreme Court to allow same-sex marriage to resume in California, wading into the protracted legal battle over Proposition 8 and giving gay-rights advocates a new court ally.

After first suggesting it would not get involved, the Obama administration will file a friend-of-the-court brief late today in support of the two gay couples who launched the fight over the issue four years ago, the officials said. Today is the last day for filing briefs in support of the couples' position.

The administration last year signaled it might stay on the sidelines. In May, when President Obama first said that "same-sex couples should be able to get married," he added that it was not a matter for the federal government.

Related: 100 Republicans sign brief to the Supreme Court arguing that gays and lesbians should be allowed to legally wed

But he appeared to express a different view in January during his inaugural address when he said, "Our journey is not complete until our gay brothers and sisters are treated like anyone else under the law, for if we are truly created equal, then surely the love we commit to one another must be equal as well."

Recommended: Committee punts on gun laws until next week

The Supreme Court hears oral arguments in late March to decide the fate of Proposition 8, an amendment to the state constitution approved by 52 percent of California voters in 2008. It banned same-sex marriages in the state and went into effect after 18,000 gay couples were legally married earlier that year.

The House of Representatives yesterday passed a Republican debt-ceiling proposal providing that if either chamber of Congress hasn't passed a budget resolution for the upcoming fiscal year by April 15, the congressional payroll office must withhold the paychecks for the members of that body.

In other words, they wouldn't get paid until they act or until the current session of Congress ends in 2015.

But is that provision constitutional?

The 27th Amendment, added to the Constitution in 1992, is intended to prevent members of Congress from giving themselves a raise. But it doesn't merely say that any raise can't take effect until the next Congress. It says members cannot vary their own pay.

Here's the entire text of the amendment: "No law, varying the compensation for the services of the senators and representatives, shall take effect, until an election of representatives shall have intervened."

The debt limit bill, said House Ways and Means Committee Chairman Dave Camp, "was carefully crafted to comply with the requirements of the 27th Amendment."

"The amount that members are paid will not be reduced nor will it be raised," Camp said during Wednesday's House debate. "There is no requirement in the 27th Amendment which states that members have to be paid weekly, biweekly, monthly, or bimonthly, or what have you, only that the pay that they receive will not vary."

Not so, said Rep. Robert Brady, a Pennsylvania Democrat, who believes putting the money in escrow, as the House bill provides, doesn't solve the issue. "If you aren't getting a paycheck in a month and you're going to wait for 18 months, that's varying. So it could be -- and, in my opinion, it is -- a constitutional problem," he said.

Who's right? Does holding the checks, but ultimately giving members their money, avoid a constitutional defect?

Professor Michael Froomkin of the University of Miami School of Law doesn't believe it's constitutional.

"I don't think this is even a close question: In my view, the escrow provision clearly does not [avoid the constitutional defect]," Froomkin said.

"The prohibition on varying the compensation seems pretty clear to me. It means no changes in amount and no changes in time of payment, because there is a time value to money. Anyone who gets a salary would think it a very material change in the terms if the money were escrowed for more than a year and a half instead of being made available to pay the mortgage," he added.

The opposite view came in a statement released by the House Ways and Means Committee, written by conservative lawyers David Rivkin and Lee Casey. "It is creative, it is fiscally responsible, and it is attentive to the text and structure of the Constitution," they said.

Some consideration was given to putting the deferred paychecks into an interest-bearing account, but Republicans rejected that idea, concluding that it would increase members' pay in clear violation of the 27th Amendment.

The Supreme Court has never interpreted the amendment, and no member of Congress has yet come forward to suggest suing over the escrow provision. Given the Supreme Court’s narrow view of who has legal authority to sue, it’s likely only a member of Congress who had a paycheck withheld would have the proper standing to challenge it.

The U.S. Supreme Court has set aside two days in late March to hear oral argument on the same-sex marriage cases.

On Tuesday, March 26, it will take up the fight over California's Proposition 8, which banned same-sex marriage in the state.

The next day, Wednesday, March 27, it will hear the challenge to the federal Defense of Marriage Act, which bars the federal government from recognizing same-sex marriages in the states where they're legal.

The U.S. Supreme Court term that begins Monday promises to be one of the most important for civil rights in decades, with the potential for blockbuster decisions on issues from race in classrooms and the voting booth to legal recognition for same-sex marriage.

Related: Conservatives warily ponder prospect of an 'Obama court'

Less than a decade after ruling that the nation's colleges and universities can consider the race of student applicants to achieve more racially diverse campuses, a practice now widely used by the nation's selective schools, the court has agreed to take a fresh look.

The new challenge comes from Abigail Fisher, a white student denied admission to the University of Texas at Austin. The school admits the top 10 percent of academic performers from all Texas high schools, then considers the race of applicants as one factor in admitting the remainder of an incoming freshman class.

Evan Vucci / AP

People who waited in line overnight to hear the Supreme Court on a landmark case on health care hold their belongings as they make their way into the court in Washington, Thursday, June 28, 2012.

Fisher did not finish in the top 10 percent at her high school and claims that the consideration of race in reviewing applications cost her a spot at the university. 

"There were people in my class with lower grades, who weren't in all the activities I was in, who were accepted into UT. And the only difference between us was the color of our skin," she said. 

The university, backed by civil rights groups, contends that while the top 10 percent plan achieves some campus diversity, many of its classes would have only a few, if any, black and Hispanic students without additional considerations of race. 

Making it harder to achieve the diversity colleges need, argues Gregory Garre, a Washington, D.C. lawyer representing the University of Texas, "would jeopardize the nation's paramount interest in educating its future leaders in an environment that best prepares them for the society and workforce they will encounter." 

The Supreme Court that will hear the case Oct. 10 is different from the one that upheld a race-conscious admissions program at the University of Michigan law school in 2003. 

"Sandra Day O'Connor was on the court then, and she's been replaced by Samuel Alito, who has much less tolerance for affirmative action," says Tom Goldstein, a Washington, D.C. lawyer who specializes in Supreme Court cases. 

O'Connor, who wrote the decision in the Michigan case, retired from the court in 2006. 

As a result, says Pamela Harris, a former Obama administration official in the Justice Department, "I don't think anyone thinks affirmative action is long for this world." 

Justice Elena Kagan, considered one of the court's liberals, will sit this one out. She was the Obama administration's solicitor general when the Justice Department became involved in the case in the lower courts. 

The Supreme Court will take up another racially charged issue this term if, as seems likely, it agrees to consider efforts to scale back the landmark Voting Rights Act. 

Passed by Congress in 1965 and renewed four times since then, most recently in 2006, a key provision requires states with a history of discrimination at the polls to get federal permission before making any changes to election procedures -- from redrawing congressional district boundaries to changing the locations of polling places. 

Three years ago, the Supreme Court brushed off a challenge to that requirement but strongly suggested that several justices had doubts about its constitutionality, given recent electoral reforms. 

"Things have changed in the South," the court said in 2009. "Blatantly discriminatory evasions of federal decrees are rare." 

Pending cases ask the court to strike down the pre-clearance requirement entirely or throw out the list of areas, consisting of nine entire states, and of 12 cities and 57 counties elsewhere, that must get permission to modify their election procedures. 

The current map, says Bert Rein, a Washington, D.C. lawyer representing Shelby County, Ala., includes some localities that have made substantial reforms while missing other parts of the country that have failed to root out discrimination at the polls. 

As a result, Rein says, the system is unfair. "Florida has been forced into pre-clearance litigation to prove that reducing early voting from 14 days to 8 is not discriminatory, when states such as Connecticut, Rhode Island and Pennsylvania have no early voting at all." 

But Debo Adegbile of the NAACP Legal Defense and Education Fund says the current map is a close enough fit to cover the areas of greatest concern. 

"Congress is not a surgeon with a scalpel when it acts to legislate across the 50 states. But it can reasonably attack discrimination where it finds it," he says. 

The court is almost certain to take up a host of challenges to the federal Defense of Marriage Act (DOMA) signed into law by President Bill Clinton in 1996. 

It defines marriage, for the purposes of federal law, as "only a legal union between one man and one woman as husband and wife." As a result, same-sex couples who get married in the states where such marriages are legal are accorded state and local benefits but miss out on more than 1,100 federal ones. 

After at first defending the law, the Obama administration notified federal courts early last year that it concluded the law was unconstitutional. House Republicans then took up the law's defense. 

A Supreme Court ruling striking down DOMA as discriminatory would not force states to permit same-sex marriage. But it would require the federal government to recognize those marriages where they are legal. 

The court could address the issue of same-sex marriage more directly if it takes up the legal challenge to California's Proposition 8, which banned gay marriage in the state.  

Legal experts differ on whether the court is prepared to go that far, rather than deciding the DOMA issue now and coming back to the constitutionality of gay marriage in a later term. 

"We're not at the point where the Supreme Court will require the state of Mississippi to allow same-sex marriage," says Louis Michael Seidman of the Georgetown University Law Center. 

Among other questions the justices will confront: 

- Must police get a search warrant before taking a blood sample from a suspected drunk driver? 

- How far can police go in using drug-sniffing dogs outside someone's house? 

- Can a 1789 law, the Alien Tort Statute, be used to bring lawsuits in US courts for violations of international law that occur in other countries? 

- And, in an issue of growing interest to U.S. businesses, should more limits be placed on the ability to bring class-action lawsuits?

Even though Pennsylvania officials offered no evidence that in-person voter fraud has tainted past elections -- or is likely to occur this fall -- a state court judge ruled Wednesday that challengers of a new photo ID requirement failed to meet the legal requirement to get it put on hold.

Lawyers for the challengers say they will immediately appeal, hoping to get enforcement of the law stopped before the presidential election on Nov. 6.

"I am not convinced any qualified elector need be disenfranchised" by the law, said Commonwealth Court Judge Robert Simpson, a Republican, in denying a request for a court order to stop enforcement of Pennsylvania's Act 18, passed by the legislature in March. It requires voters to present a photo ID at the polling place in order to vote.

Several voting rights groups, including the League of Women Voters and the NAACP, joined with a group of state residents to claim that the law would force thousands of people to say home on election day because they lack the kinds of ID cards required by the new law.

At most, Judge Simpson said, the percentage of registered voters in the state without a qualifying photo ID "is somewhat more than 1% and significantly less than 9%." 

But he said that with the availability of absentee voting, the right of a person without photo ID to cast a provisional ballot, and the opportunities for those with special hardships to seek individual help from the courts, he was not convinced that any of those who filed the lawsuits or the witnesses they called will be prevented from voting.

The judge also said the challengers failed to meet the legal test required to mount what's known as a facial challenge to a law -- a claim that the law on its face is unconstitutional.  "They do not acknowledge the extremely rigorous legal standard for facial challenges requiring a demonstration that there are no set of circumstances under which the statute may be valid."

Similar efforts to stop voter ID laws in other states have been unsuccessful in federal court, which is one reason why the challengers in Pennsylvania decided to sue in state court by claiming that the law there violated the state constitution.

While opponents of the law are hoping they can prevail on appeal in the state courts, one election law expert believes today's ruling will ultimately survive.

"The decision is almost certain to stand," said professor Rick Hasen of the UC Irvine School of Law, author of "The Voting Wars."

The Pennsylvania Supreme Court, he said, is divided 3-3 between Democrats and Republicans, who are likely to support today's ruling.

But even if they did split along party lines, Hasen said, "a 3-3 tie leaves the lower court opinion in place. I don't expect there would be any fuller ruling on the merits in this case before November, or that any such ruling would lead to a different result."

Three times on "Meet the Press" last Sunday, House Minority Leader Nancy Pelosi said the payment individuals must eventually make for failing to buy insurance under the health-care law is a penalty, not a tax.

"It's a penalty that comes under the tax code," Pelosi said, "for the 1%, perhaps, of the population who may decide that they're going to be free riders" by not buying insurance.

Moderator David Gregory persisted. "But it's a new tax. It is a new tax on the American people," he said.

"No, no, no, no," Pelosi responded. "It's not a tax. It's a penalty for free riders."

So what is the payment that virtually all citizens must make if they decline to obtain health insurance when that provision of the Affordable Care Act takes effect in 2014?

In his Supreme Court opinion declaring the law constitutional under Congress's taxing authority, Chief Justice John Roberts called it a tax no fewer than 26 times. The health-care law itself repeatedly refers to the payment as a penalty, but Roberts said that didn't matter. The conclusion about what it is, he said, "should not change simply because Congress used the word 'penalty.'" 

For him, the issue is how it actually works, not the label attached to it in the statute.

Penalties, Roberts said, work much differently from taxes. Quoting an earlier Supreme Court decision, he said a penalty "is an exaction imposed by statute for an unlawful act." But failing to buy health insurance is not unlawful, because a citizen has an alternative -- either buy insurance or pay a tax. The conclusion: It cannot be a penalty.

"Neither the Act nor any other law attaches negative consequences to not buying health insurance, beyond requiring a payment to the IRS," Roberts wrote. "The shared responsibility payment merely imposes a tax citizens may lawfully choose to pay in lieu of buying health insurance."

It is, he put it succinctly, “a tax on going without health insurance.”

Is all this semantics, or does it matter? It made all the difference to Chief Justice Roberts. His opinion makes it amply clear that if he thought it wasn't a tax, he would not have voted to find it constitutional. Under the law of the case, the Supreme Court declared that payment a tax, not a penalty.

The Supreme Court has upheld the healthcare law, upholding the individual under the taxing authority of congress, not the commerce clause.

It was indeed a 5-4 decision, but with Chief Justice Roberts voting with the liberal majority.

Watch NBC's live analysis and coverage here.

*** UPDATE *** Here's the court's entire opinion.

*** UPDATE 2 *** President Obama is expected to speak from the White House at 12:15 pm ET.

*** UPDATE 3 *** We expect to hear from Mitt Romney at 11:45 pm ET.

In addition to its ruling on Arizona's immigration law, the U.S. Supreme Court today declined to revisit its controversial 2010 Citizens United decision, which permits corporations and labor unions to freely make independent expenditures in political campaigns.

What's more, in a 5-4 vote, "the majority summarily reversed a decision of the Montana Supreme Court that had refused to follow the Citizens United decision," the New York Times says.

The case involved Montana's Corrupt Practices Act. It requires corporations in the state to form what are essentially political action committees (PACs) and to spend only money that was given voluntarily by employees and shareholders. When the law was challenged as contrary to the Citizens United decision, the Montana Supreme Court upheld it as justified by the state's long history of political corruption. Besides, the state court said, the law doesn't run counter to Citizens United because corporations in Montana can still express their political views through the voluntary PAC-type funds. State regulations, the court said, are far simpler than federal campaign funding rules, imposing no real burden on corporate expression.

Once the House committee votes in favor of citing Attorney General Eric Holder in contempt, it goes to the full House for consideration.

If the full House votes in favor of the contempt citation, the issue is sent to the U.S. attorney for the District of Columbia. A federal law adopted by Congress in 1857 directs federal prosecutors to refer these matters to a grand jury for possible prosecution. The language is mandatory as to the U.S. attorney: "whose duty it shall be to bring the matter before the grand jury for its action."

But from there on, it gets complicated.

The Justice Department has long taken the position, as a separation of powers matter, that Congress cannot force the Justice Department to undertake a prosecution of an executive branch official. The courts have never resolved the question. 

The Justice Department, under both Democratic and Republican administrations, has further claimed that a U.S. attorney must not initiate a prosecution when the president has asserted executive privilege over what Congress seeks.

The administration of George W. Bush most recently made this claim during the congressional investigation of the firings of several U.S. attorneys nationwide. Congress subpoenaed former White House counsel Harriet Miers and Chief of Staff Josh Bolton, and the president directed that neither should testify or produce the requested documents. Though the broad issue of executive privlege went to court, it is still unresolved.

Another gray area here is how much a president can cover under the umbrella of an assertion of executive privilege. The further a matter gets from the White House and presidential decision making, the more the courts have been unwilling to recognize it.

On a broader point, the federal courts have been reluctant to referee what they see as fights between the White House and Congress. During the legal battle over Miers, the federal district court in Washington practically begged the two sides to work it out without suing each other.

"The court strongly encourages the political branches to resume their discourse and negotiations in an effort to resolve their differences constructively," it said.

And finally, there's this point to remember: if this does end up in court, it could take up to two years to resolve, given the time for a trial and subsequent appeals. However, a contempt citation is valid only during the Congress which approved it. Each term of Congress lasts only two years, so if the issue was still in the courts when this Congress ends in a year and a half, the contempt citation would evaporate, and so would any lawsuit.