As it happened: Supreme Court ruling

Good morning from the BBC's Washington bureau. This morning the US Supreme Court is set to hand down its decision on whether President Barack Obama's signature healthcare reform is legal under the terms of the US consitution.

It is one of the biggest news days of Mr Obama's term in office, and we'll be bringing you news and commentary as the morning unfolds. Stay with us to hear from our team of correspondents, from the smartest analysts in Washington, and reaction from all sides in the healthcare debate - from politicians to ordinary Americans.

Here's a bit of background to get the ball rolling this morning: The US lacks a single-payer or tax-based healthcare system like the UK's National Health Service. Most Americans receive care through a patchwork of private insurance plans provided by employers or bought on the open market, and government-run programmes for the poor, elderly and veterans.

About 50m Americans lack health insurance altogether. Since the mid-20th Century US presidents have sought to reform the healthcare system. After a bitter and protracted battle, Mr Obama and Congressional Democrats succeeded in passing the Affordable Care Act in 2010.

The law was derided by its opponents as "Obamacare" - you'll hear that term a lot today. Its centrepiece was a requirement that Americans obtain insurance or pay a tax penalty. Whether that requirement is constitutional is at the centre of today's eagerly anticipated ruling.

The Supreme Court session opens today at 10:00 local time (14:00 GMT) at its stately building directly opposite the US Capitol here in Washington. The court is expected to announce its healthcare decision at about 10:15 local time.

The crowd outside the Supreme Court has now swollen, the pavement is rammed with protesters and demonstrators, milling around (if they can move) and chanting. It's a great American scene.

The buzzer has sounded in the Supreme Court, signalling that the justices are set to emerge from their chambers with some decisions in hand.

Here's a handy graphic we've put together to illustrate the extent of the US healthcare insurance issue.

Source: US Census Bureau

We're hearing the healthcare decision has just come down.

News of the ruling is complex and nuanced. ScotusBlog says: "The individual mandate survives as a tax" and "The mandate is constitutional. Chief Justice Roberts joins the left of the Court". ABC News says the individual mandate is allowed.

Tom Goldstein at ScotusBlog writes: "The bottom line: the entire Affordable Care Act is upheld, with the exception that the federal government's power to terminate states' Medicaid funds is narrowly read."

Dancers and drummers and protesters have crowded outside the court.

The insta-reaction begins: Matt Kibbe, head of anti-tax conservative Tea Party group Freedom Works, writes this in a fundraising appeal to supporters: "In a shocking and disappointing verdict, the Supreme Court upheld ObamaCare and its individual mandate as a tax, ushering in an unprecedented expansion of government power and handing a huge victory in Obama's Progressive plan to 'fundamentally transform America.'"

SCOTUS stressing that it is a tax: also saying that as such people cannot pay it. Grist to the Tea Party mill.

Some explanation of what has just happened: the individual mandate has been upheld within Congress' power in the "Taxing Clause" (Article1, Section 8, Clause 1 of the United States Consitution). In a nutshell: The charge on those who do not acquire a suitable insurance will be a tax authorised by the taxing clause. And so the individual mandate as a whole will be a valid exercise of Congress's taxation power. Is that clear enough?

Republican Party Chairman Reince Priebus says the ruling in favour of President Obama's healthcare reform raises the stakes for the November election: "We need market-based solutions that give patients more choice, not less. The answer to rising health care costs is not, and will never be, Big Government." In other words, vote Republican.

Those two provisions have proved broadly popular, even though the healthcare law as a whole polls badly with the US public

What next? In 2014, the individual mandate kicks in: Americans will be required to buy insurance if they don't have it through their employers or the government. On the other hand, insurance companies will be barred from rejecting customers just because they are already ill.

Here's how the justices voted: To uphold: Roberts (Chief Justice), Ginsburg, Sotomayor, Breyer, Kagan. Dissenting (to overturn): Kennedy, Scalia, Alito, Thomas

Chief Justice Roberts was appointed by President George Bush, a Republican, in 2005. He was the only of the nine justices to cross party lines, so to speak.

The full decision penned by Chief Justice John Robrts is available on the Court's website here. This ruling will go down in history, and Chief Justice Roberts' words are worth a read.

Healthcare reform supporters outside the Supreme Court rejoiced and cheered after hearing of the ruling.

There are predictably opposing reactions from the two key party leaders in the Senate. Here's the first, Democratic Majority Leader Harry Reid: "Now that this matter is settled, let's move on to other things. Like jobs."

And here's the second, reaction from Senate Minority Leader Mitch McConnell, a Republican: "We've passed plenty of terrible laws around here that were constitutional." On the Senate floor, he declared the only way to fix the law was "full repeal".

Some statements from the key players coming soon: Mitt Romney will speak at 11:45 EST (15:45 GMT) and President Obama will deliver a statement to the press at 12:15 local time (16:15GMT).

Key words from the top of the Supreme Court decision: "We do not consider whether the Act embodies sound policies. That judgment is entrusted to the Nation's elected leaders. We ask only whether Congress has the power under the Constitution to enact the challenged provision."

In the decision, Chief Justice Roberts notes that tension between the powers of the states and the federal government has been part of the American system since the beginning. "In this case we must again determine whether the Constitution grants Congress powers it now asserts, but which many states and individuals believe it does not possess."

On Fox News, presenter Chris Wallace says the decision will energise Republican voters who will now see the only way to be rid of the healthcare reform law is to put Mitt Romney in the White House. The stridently anti-tax Republicans will now reframe the argument as a debate about the "Obamacare tax", he predicts.

We'll be carrying the statements from Mitt Romney and President Obama here over the next 30 minutes or so. Check your video window if you're viewing this on a desktop computer for the live feed.

Democratic Congressman Luis Gutierrez, an Illinois liberal, says: "This will literally help people live who before this law, if they were sick and couldn't afford care or couldn't switch health policies, were sentenced to death or poverty or both. Today's ruling makes a definitive statement about how dearly we hold the values of equality and opportunity in the United States."

Mitt Romney is up, denouncing the Obama healthcare law as "bad policy".

Romney continues: It's a "job-killer", it raises taxes, and "Obamacare puts the federal government between you and your doctor."

Romney: "Help us defeat Obamacare, help us defeat the liberal agenda" and a government that is "too big". No recognition from him, of course, that he himself passed America's first individual healthcare mandate while governor of Massachusetts.

The lecturn at which Romney stood bore a sign reading: "Repeal & Replace OBAMACARE". That seems to be the new mantra from the Republicans.

President Obama is in the East Room. He says the court reaffirmed "a fundamental principle" of America: "No illness or accident should lead to any family's financial ruin."

Obama: The law won't affect insurance Americans already have. But now, he says, insurance companies can't drop your coverage if you get sick, "jack up your premiums without reason", and can't reject people with pre-existing conditions.

Obama is explaining the law in measured tones, using the opportunity to speak to the nation on an issue that has seen advocates of both sides ratchet up the rhetoric in recent years.

Obama: It is now the "responsibility" of people who lack insurance to buy it.

Obama: If you do not currently have insurance, in 2014 you'll have better access to affordable insurance through state-run health insurance markets. "They won't be able to charge you more just because you're a woman. They won't be able to bill you into bankruptcy."

Obama wraps it up: "These are the Americans for whom we passed this law. The highest court in the land has now spoken. We will continue to implement this law. But what we won't do.. is refight the political battles of two years ago. It's time for us to move forward, to implement and where necessary improve on this law."

In his speech, Obama made the case for the law's details: "These provisions provide common-sense" protections to middle-class families. He said they enjoy "broad" popular support.

Just in case you're not quite sure what the Dred Scott decision was... It denied blacks US citizenship in 1857 and said they were not afforded the protections of the US constitution. It was overturned by the 14th amendment to the constitution in 1868.

We have come to the end of a tumultuous morning of news. The US Supreme Court upheld President Obama's signature policy achievement: a 2,700-page healthcare reform law. With that, the Republicans renewed their effort to use "Obamacare" as a cudgel to beat him and the Democrats now and in the November election.

Stayed tuned through the day to the BBC News website for more analysis, coverage and commentary on the Supreme Court decision and the political fallout.