For perhaps the first time since Scotland was pushed into a political union with England in 1707, it faces a realistic possibility that it could once again stand alone.

The debate about an independence referendum, which gained traction in Scotland following a 2011 electoral victory for nationalists, reached a fever pitch this week when the United Kingdom government insisted it could dictate the terms of the referendum, kicking up a surge of Scottish nationalist anger.

In a landmark moment for the independence movement, the pro-independence Scottish National Party won an overall majority in Scottish elections for the first time in May 2011. After their strong showing, the new administration promised to hold a referendum on whether or not to break away from the UK during the second half of their five-year term. The favored date is sometime in 2014, near the end of the current British administration's time in office.

But earlier this week, British Prime Minister David Cameron insisted that a referendum would only be legally binding if it is held in the next 18 months, insisting that Scotland does not have the ability to call a legally binding referendum.

Public support for outright independence today remains well below a majority – 38 percent, according to the most recent polls – so even if the referendum happened, it might not lead to independence.

First Minister Alex Salmond, the head of the Scottish government, says he wants to wait until the second half of his term in order to fulfill his pledge. Some say he wants to wait so that he can tap into an expected rise in nationalist sentiment in 2014, which marks the 700th anniversary since Scotland's last famous military victory against England – with current levels of support for independence, a "yes" is unlikely.

Whose call is it?

Members of the Scottish government bristled at Mr. Cameron's comments on their referendum plans. Deputy First Minister Nicola Sturgeon accused Cameron of interfering in a matter that was for "the Scottish people to decide," insisting that the prime minister lacked a mandate in Scotland because his Conservative Party holds only one of the 59 Scottish seats in the UK parliament.

According to the constitution, the Scottish Parliament does not have power over areas such as constitutional changes (as the referendum would be), national defense, central taxation, immigration, or foreign policy.

Amid the ensuing furor from Scots, Cameron backpedaled, denying he was trying to dictate the terms of the referendum. "We have set out very clearly that we are actually making sure that people in Scotland can determine their own future," he said. "It is for them to do that and quite rightly the British government is responding to that desire."

The UK government's Secretary of State for Scotland Michael Moore, educated in Scotland, said on Jan. 10 that the devolved Scottish government lacked the right to hold a legally-binding referendum and insisted that the UK government has the right to dictate some of the terms of the referendum, including the date, so that results are beyond the reach of potential lawsuits.

Although the UK government does not believe in independence, it wants the Scots to have a referendum that is "decisive and fair," Moore said. He also insisted the vote should be held "sooner rather than later" in order to avoid economic uncertainty; some say that big business has been deterred from investing in Scotland because of the independence debate.

Parties that favor remaining with the UK, known as pro-union, have also pushed for the referendum to be held at the earliest opportunity. "We want the referendum to be held as quickly as possible and we want it to be run in Scotland," said Johann Lamont, the recently installed leader of the pro-union Scottish Labour party, which holds the second largest bloc in the Scottish Parliament.

In response to Westminster's statements, Mr. Salmond announced that the referendum would be held in 2014. His party says its majority in parliament makes it clear that they have a mandate from the Scottish people to dictate the terms.

Prof. James Mitchell, an expert in nationalism and regionalism based at the University of Strathclyde in Glasgow, still believes the referendum will take place in the second half of the Scottish Parliament "because it is in the interests of the SNP [Scottish National Party]" and the Scottish people."

Without the UK, there's Europe

The debate about the broader issue of independence has been clouded by rhetoric from both sides since the May election, which put independence on the agenda in a serious way because of the nationalists' victory.

One of the more enduring criticisms of Salmond and the Scottish National Party has been that their lack of clarity about a date for the referendum has hurt the Scottish economy. Cameron's spokesman recently said that leaving the future of the union uncertain "can have a detrimental impact on the economy."

But Salmond made substantial gains after Cameron's December veto of a new European Union treaty that was intended to create a stronger fiscal union for the EU. The veto was met with warnings of increasing British isolation and anger from the Continent. Salmond, who poured scorn on the prime minister's decision, could use the veto to drive a wedge between Scotland and England, and portray independence as a way to avoid isolation and move closer to Europe, say analysts.

Beyond 'yes or no'

There is a third option that could be included in the referendum: "devolution-max." This option would include more powers for Scotland, but fall short of total independence.

Cameron and other unionists want a simple "yes or no" vote on independence, according to government figures. Although the Scottish Nationalist Party also favors that approach, it is also more mindful of Scottish public opinion, which seems to reflect a preference for greater economic and fiscal powers, but not a complete split. According to one recent poll, nine out of 10 Scots support "devo-plus," which would afford Edinburgh more tax-raising powers, among other things.

Mr. Mitchell says the inclusion of a third option – and possible vote in favor of devolution-max – would make Scotland's future "interesting" because the nationalist party's raison d'etre is independence. It would have to reevaluate much of its platform.

The stand-off could result in a non-binding referendum, which would still have a significant impact on the debate. "The moral and political force of a vote for independence would be enormous, and impossible for a future government to ignore," the Scottish government said on its website.

Referendum wrangling aside, the nationalists face tough questions about what an independent Scotland would look like, from the economy, to the currency, to matters of defense and security. Pro-independence Scots point to already present investment in areas such as renewable energy as evidence that the Scottish economy could prosper post-independence.

Despite his party's success, old anxieties and suspicions over Salmond's true intentions persist. Salmond is a shrewd political operator with an economist's sharpness who has led the push for Scottish independence for more than 20 years. No other Scottish parliamentary poitician is considered capable of rivaling him on charisma or his grasp of the finer points of public policy. But the possibility of a third option in the referendum has drawn accusations that he is running scared that the Scottish electorate does not back his one true ambition: a free Scotland.

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The idea of "devolution-max" carries weight because after three centuries of being tied to England, many Scots are skeptical of their country's ability to stand alone.

"I don't know if Scotland could survive on its own. We don't have a lot of industry, do we?" says Una McKain, a pensioner from Buckhaven, a town at the heart of a former Fife mining community that went into severe economic decline after the area's coal mines closed. "I don't trust Alex Salmond. He is arrogant, self-interested like the rest, and has done nothing for the working class."