Law enforcement sources say the FBI has arrested an agent of Pakistan's official state intelligence service, accusing him of making thousands of dollars in political contributions in the United States without disclosing his connections to the Pakistani government.

Syed Ghulam Fai will appear in federal court this afternoon in Alexandria, Virginia.  He's not charged with being a spy. But he is charged with being an unregistered agent or lobbyist of the Pakistani government.

He's the exective director of a group called the Kashmiri American Council, the sources say, and he has given tens of thousands of dollars to congressional candidates and party organizations. U.S. officials say there's no reason to believe that members of Congress or other organizations that received his contributions were aware of his government connections.

A call to the Kashmiri American Council's office in Washington went unanswered this morning. 

Handing out the final decisions of the current term, the Supreme Court issued two -- one of which is related to politics.

It invalidated, by a 5-4 vote, a 1998 Arizona law that gave a financial boost to publicly funded candidates if their privately funded opponents spent more money.

Under the law, candidates who declined to accept campaign contributions could participate in the public financing system, which gave them a lump-sum grant for the campaign. But if an opponent, who was not publicly funded outspent the amount of the state grant, the publicly funded candidate received more money from the state to bring the candidates into rough spending parity.

The system was challenged on First Amendment grounds by several privately funded candidates, who claimed that they reined in their spending to avoid triggering the matching funds for their publicly funded opponents. The law, they argued, acted as a restraint on their campaigns and thus violated their free-speech rights.

From NBC's Pete Williams
A unanimous US Supreme Court today ruled that former attorney general John Ashcroft cannot be sued by a American-born Muslim man who claimed that he was improperly detained in the early days of the war on terror. The ruling is a blow to civil liberties groups who challenged a controversial post-9/11 policy.

The lawsuit was brought by Abdullah al-Kidd, who was arrested by the FBI as he sought to board a flight to Saudi Arabia in March 2003 for what he claimed was a study-abroad trip.

The government said he was needed to testify at a trial in Idaho of a man accused of helping al Qaeda run a computer-based recruiting network. Al-Kidd was held for 16 days as a material witness, but he was never called to testify at the trial.

Al-Kidd claimed his arrest amounted to unconstitutional preventive detention, and he said then-attorney general Ashcroft's approval of the practice amounted to a kind of "round up the usual suspects" policy forbidden by the Constitution. Lower courts said Ashcroft could be sued, but the Supreme Court today threw the case out.

The court held there was no constitutional violation, and even if there was, Ashcroft would be protected by the immunity public officials enjoy from lawsuits over their official acts.

From NBC's Pete Williams
In a victory for the Obama administration, a federal appeals court panel has lifted an injunction on the use of federal money to pay for research using embryonic stem cells.

Since 1996, Congress has banned the use of federal funds for research in which embryos were destroyed. President Obama acted to expand the use of stem cells by permitting the federal government to support research only on the stem cells themselves -- not the actual gathering of the cells from embryos, a policy which the administration said was entirely consistent with the law. But last year, a federal judge in Washington ruled that because embryos must be destroyed to get those cells, the congressional limitation bans using federal money on anything done with the cells later.

Today, by a 2-1 vote, the appeals court threw that injunction out, finding that the congressional research limitation is ambiguous. The federal government, it said, "seems reasonably to have concluded" that although the congressional ban blocks funding for the destructive act of deriving a stem cell from an embryo, it does not prohibit funding a research project in which such a cell will be used.

The government allows research using only stem cells derived from embryos that were created by in vitro fertilization for reproductive purposes and would otherwise be destroyed.

Last year's injunction threatened about 200 research projects that relied on federal money already granted. Because these grants were renewed every year, many of the researchers said they'd have to stop when the money ran out.

The National Institutes of Health is expected to comment on today's ruling later in the day.

From NBC's Pete Williams
Experts on the military justice system agree that President Obama was unwise to make a comment last week about Army Private Bradley Manning, accused of giving classified US government documents to Wikileaks. But they disagree about whether the statement will undermine the military's prosecution of Manning.

After a fundraising event in San Francisco last Thursday, the president was approached about the Manning case, an encounter recorded on cellphone video and uploaded to the Internet. After explaining that federal law prohibits the unauthorized disclosure of classified documents, Mr. Obama said, "He broke the law."

Presidents and other senior officials often make statements about the guilt of defendants who are awaiting trial before a jury. What's different about this case, however, is that President Obama is the commander-in-chief of the military, and Manning will be tried before a military court.

Rules for courts martial ban the exertion of "undue command influence." Many supporters of Pvt. Manning have argued that his trial is now tainted because the president, the nation's most senior commander, has pronounced judgment that Manning is guilty. 

In an op-ed appearing in Wednesday's Los Angeles Times, a former military prosecutor says many critics of the court-martial system often believe that military jurors simply ask themselves one question, referring to their commanders: what does the Old Man want us to do?

"When the jurors retire to the deliberation room at the Manning court martial, they will not have to speculate on the answer; arguably the most important 'Old Man' of them all has spoken, and he said Manning is guilty," writes Morris Davis, a retired Air Force officer and former prosecutor at Guantanamo.

The president should have been more circumspect, agrees Eugene Fidell, an expert on the military justice system. But he believes Obama's comment will not affect the outcome of Manning's trial.

"It will generate motions by the defense and will require some care in selecting the military members of the jury, a process already complicated by the extensive press coverage of this case," Fidell said. "It was going to have to be a very careful questioning process for potential jurors, to ask if they have seen reports or read about the case. Now they'll also have to be asked whether they heard the president's comment and if that would make any difference to them. But that will be the extent of it, and they'll get on with the trial."

From NBC's Pete Williams
Six states, New York City, and three conservation groups ran into a buzz saw at the U.S. Supreme Court today, likely signaling an end to their legal battle against five big power companies over global warming.

The Supreme Court Building is seen last month on Capitol Hill in Washington. (AP)

They filed their lawsuit in 2004, hoping to have a legal fallback ready in the event the Environmental Protection Agency chooses not to impose carbon dioxide pollution limits on existing power plants. The states, New York, and the conservation groups -- collectively, the plaintiffs -- claimed that those power plants were creating a public nuisance, releasing greenhouse gasses that contribute to global warming and cause environmental damage. The power plants they targeted, their suit said, emit ten percent of the entire country's carbon dioxide pollution.

But based on comments from the justices during today's oral argument, it's doubtful the plaintiffs have a single vote on the court in favor of keeping their lawsuit going. Chief Justice John Roberts noted that the EPA has decided to look at whether CO2 emissions from existing plants should be regulated. "Doesn't that mean that this federal action displaces any right to sue under common law?" he asked.

Even the court's more liberal justices hinted that they doubted the plaintiffs could keep their public nuisance suit going. "The relief you seek sounds like what the EPA does. You want to turn federal judges into a super-EPA," said Justice Ruth Bader Ginsburg. 

The justices were also skeptical that the plaintiffs could successfully attribute a measurable change in global warming -- a worldwide phenomenon -- to a single group of polluters. The states claim they can do so based on past cases in which one state sues a company in another state for causing pollution that creates a public nuisance. "But there's a huge gap or chasm between state pollution cases and this global one," said Justice Elena Kagan. 

The EPA has said it will decide by May of 2012 whether to regular CO2 emissions from existing plants. Environmental groups wanted this lawsuit to be a fallback in the event it views the EPA's action as insufficient. But it now seems doubtful that legal safety net will be available.

From NBC's Pete Williams
Federal law prohibits government employees from coming to work during the shutdown except for those needed in "emergencies involving the safety of human life or the protection of property."

So how does that amount to the roughly 60 percent of the federal workforce?

A 127-year-old law, the Antideficiency Act, bans the government from spending money, or incurring debts, that Congress hasn't approved.  That means in a shutdown, federal employees cannot come to work and earn a salary, for which they would have to be paid.

Congress amended that law in 1990 to specify which federal employees would be granted exceptions and required to continue working to cover emergencies. The  new law says emergencies worthy of an exception do not include "ongoing, regular functions of government, the suspension of which would not imminently threaten the safety of human life or the protection of property."

A 1995 internal Justice Department legal memo said the law must be interpreted narrowly -- "only when a threat to life or property is imminent" and "of such a nature that immediate action is a necessary response to the situation."

It's an understatement to say the law has been read generously. "It's more a matter of custom than strict interpretation," says a former Justice Department official.

Broad exceptions are made for virtually the entire federal law enforcement, including the FBI, DEA, ATF, US Marshals, ICE, and CPB.  Roughly 80% of employees in the Department of Homeland Security will stay on the job, including the Coast Guard and the Secret Service.  Federal meat and poultry inspectors will report for duty as usual.

A White House official says the fact that more than half of all federal employees are considered exceptions is driven by "an increase in civilian DoD and DHS personnel, as well as new sources of funding outside of appropriations -- most notable, the Veterans Administration now gets advanced appropriations, so they stay open."

The Social Security Administration is also funded by an indefinite appropriation, so many of its employees will be expected to remain on the job.

Still, the fact that roughly 1.2 million of the nation's 2 million federal employees will be on the job after the shutdown seems a departure from what the Justice Department said in 1995, when it advised the White House that the emergency exception "applies only to cases of threat to human life or property where the threat can be reasonably said to be near at hand and demanding of an immediate response."

From NBC's Pete Williams
Federal agencies are going through the agony of deciding who's essential and who isn't. Those considered non-essential are discovering that no matter how loyal or patriotic they may be, it will be a violation of federal law for them to come to work if there's a shutdown.

Federal law bars the government from spending money for expenses that haven't been approved. That means if a shutdown leaves a government agency without money, employees cannot come to work and thereby create an obligation for the government to pay them.

There's an exception to the law, however, for the "voluntary services" of federal employees who are needed to handle "emergencies involving the safety of human life or the protection of property." This language has tended to be interpreted very broadly -- to cover well over half of all federal employees, who will still be expected to come to work. Once past shutdowns have ended, Congress has paid the essential employees who continued working.

So it boils down to this: In a shutdown, federal employees cannot volunteer to come to work, unless their jobs are considered essential. And if they are essential, their "volunteering" is mandatory.

One other note: While it will be illegal for non-essential personnel to come to work during a shutdown, no one has ever been prosecuted for doing it. However, anyone who tries it -- to demonstrate how essential they think they are -- would be subject to discipline and could even be fired.

From NBC's Pete Williams
Assuming it doesn't last very long, a government shutdown would not have much effect on the federal courts.

The U.S. Supreme Court would likely go on about its business, much as it did during the last federal shutdown. Back then, a court official says, the justices and the court staff continued coming to work, and the court remained open to visitors.

The rest of the federal judiciary -- the trial and appeals courts -- have enough money to keep going for 10 days, or two work weeks, says a spokesman for the administrative Office of the U.S. courts.

"Once that funding is exhausted, however, the federal court system faces serious disruptions," the spokesman says. "Following their own contingency plans, federal courts would limit operation to essential activities." That court mean that some jury trials would be postponed.

AP

From NBC's Pete Williams
The Obama administration has decided to put Khalid Sheikh Mohammed and the other 9/11 defendants on trial before military commissions at Guantanamo Bay, Cuba, abandoning the plans to bring them to the U.S. for trial in a regular civilian federal courtroom.

Attorney General Eric Holder will announce the decision at 2:00 pm ET at a news conference at the Justice Department.

From NBC's Pete Williams and Jonathan Hutcheson
Did President Obama violate the Constitution or federal law when he ordered the U.S. military to take part in coalition attacks on forces loyal to Moammar Khaddafy in Libya?

The Constitution itself doesn't answer the question, because it gives Congress authority "to raise and support Armies," "to provide and maintain a Navy," and "to declare War." But it also provides that, "The President shall be Commander in Chief of the Army and Navy of the United States."

Congress has formally declared war only five times in U.S. history -- for the War of 1812, the Mexican War, the Spanish-American War, and World Wars I and II. But presidents have approved dozens of military actions with no such declaration, including the Korean conflict and the war in Vietnam. 

Well over 100 military operations were ordered without any advance Congressional authorization at all. Recent examples include actions in Grenada, the overthrow of Manuel Noriega in Panama, and intervention in civil wars in Bosnia, Kosovo, and Macedonia.

A federal law, the War Powers Act of 1973, requires the president to consult with Congress "in every possible instance" before deploying U.S. forces. An exception was made for emergencies created by attacks on the U.S. or its armed forces.

Some legal scholars conclude that President Obama violated the law's requirements, when he failed to seek congressional approval.

"Judging just from the pictures of what we are seeing happening on the ground, this is quite substantial, and this is the sort of thing that would have needed Congressional approval," said Professor Oona Hathaway of Yale Law School, an expert on executive power and international law.

While the president has stressed the international component of the operation, she believes that makes no difference. "The fact that the Security Council has authorized an imposition of a no-fly zone does not answer the constitutional questions," she said.

But one former official who advised President George W. Bush said that while the decision to deploy U.S. forces in the Libyan operation was a political and strategic mistake, it's entirely legal.

"Congress raises and supports the military, but the president is the commander. Declaring war and making war are two different functions. There's no question President Obama has the authority to do what he did," the official said, asking that his name not be used.

Mr. Obama's actions are consistent with the way every president since Richard Nixon has treated the War Powers Act, choosing to notify Congress only after a decision has been made to sign orders authorizing military operations.

His actions do, however, appear to contradict the view he expressed as a candidate. In December 2007, he told Charlie Savage, then of the Boston Globe that a president "does not have power under the Constitution to unilaterally authorize a military attack in a situation that does not involve stopping an actual or imminent threat to the nation." 

So who's right? Constitutional questions, and legal battles over violations of federal laws, are normally resolved by judges. But this is an area where the courts have been reluctant to tread, unwilling to referee what they see as disputes between the political branches of the government. 

From NBC's Pete Williams
In a concession to his inability to close down the U.S. detention facility at Guantanamo Bay as he planned to do when he came into office, President Obama has ordered the Pentagon to resume military tribunals for some detainees there.

Since Obama became president, no NEW cases were referred to military tribunals, but some existing cases were proceeding. This order lifts the freeze and allows new cases to be brought.

However, the policy makes clear that the administration continues to believe that some cases should be tried in civilian U.S. courts. This new policy today does not mean that ALL detainees at Gitmo will be tried in military commissions. 

In other words, the administration continues to believe that Khalid Sheikh Mohammed and other high-value detainees should be tried here, not at Gitmo, and it will continue pushing Congress to change a recently enacted law which bars bringing any further detainees to the U.S. for trial. However, if Congress is unwilling to budge, then this new policy opens up an avenue for putting Khalid Sheikh Mohammed on trial before a military commission, if it comes to that.