Greece does not have to drop the euro and it would be nearly impossible to legally remove it from the eurozone unless it went willingly, according to EU law experts.
The country was negotiating its fate in the European parliament on 8 July and received backing from many member states, who called for Germany to restructure the country's debt.
"Technically it could be said that if Greece has repudiated the [EU] treaties — and it's not clear it has — you can't have those people in the central bank," said Damian Chalmers, a London School of Economics professor of European Union law.
If Greece was found to have broken the Lisbon treaty, it could be removed from EU institutions, like its membership of the Economic and Financial Affairs Council (Ecofin).
"But to go through that would be legally difficult and politically explosive," Chalmers said. "They've got an excessive budget deficit, yes their debt is too big. What they're repudiating is repayment of their debts."
And if the Greeks want to use the euro? "No one can stop them using euros as a unit of exchange," said Chalmers. He noted Montenegro and Kosovo, who are not members of the eurozone, already do this.
"In those two terms, they can't force Greece to leave. They could stop payments. The real reason Greece might have to leave is humanitarian aid."
In search of an exit loophole
Former Greek finance minister Yanis Varoufakis stood firm on the issue on 30 June saying the EU treaties make no provision for a Grexit. "Our membership is not negotiable," he told the Telegraph.
But a report in the Financial Times on 7 July indicates EU lawyers and eurozone officials are pouring over treaties to find a loophole that would make pushing the country out of the EU legal.
"To throw a country out on the smallest technicality would be difficult," said Chalmers. "I think they're just looking for legal mechanisms for leverage."
Greece is in the "first stages of the default", he said. The country owes a total of €323bn (£230bn, $352.7bn). And if it does not strike a deal by 20 July, it will default on a €1.55bn payment to the International Monetary Fund.
Chalmers only sees one way out. But one that "no one wants to take". He said: "The European Central Bank gives debt relief to the Greeks. At that point the ECB prints more money and the Euro goes down a bit." He proposes that Greek debt be slashed 50%. In exchange "you would want much better control of the Greek state."
Rock-star economists Thomas Piketty and Jeffrey D Sachs are calling for something similar. In an open letter to German Chancellor Angela Merkel — who effectively holds the purse strings on Greece's debt to the ECB — they write: "The financial demands made by Europe have crushed the Greek economy."
Piketty is an expert in easing financial inequality. Sachs helped restructure Russia's centrally run financial institutions into a market economy following the dissolution of the Soviet Union in 1989.
They wrote: "We need to restructure and reduce Greek debt, give the economy breathing room to recover, and allow Greece to pay off a reduced burden of debt over a long period of time."
Assurances required from Tsipras
In a separate blog post, Sachs writes Greek Prime Minister Alexis Tsipras "needs to assure Merkel that Greece will live within its means, not as a chronic ward of Europe". To get this, he said: "Debt relief and tough reforms should be phased in over time, according to an agreed schedule, with each party following through on its commitments, as long as the other does, as well."
If Greece were to leave the eurozone, the economists wrote in their letter, it could "lead to far-reaching economic consequences across the world".
In the European Parliament on 8 July, various MEPs reminded Merkel that debt forgiveness for Germany following the Second World War allowed the country to get back on its feet and become the financial powerhouse it is today.
In an article set to be published in the New York Review of Books on, 9 July, written by investor and hedge fund manager George Soros, he accuses Merkel of ruling "out the possibility of a common treasury just when it was needed" following the 2008 economic crisis.
He said: "That was the beginning of the euro crisis. Crises in individual countries like Greece, Italy, or Ireland are essentially variants of the euro crisis."
Currently the unemployment rates of member states such as Spain, Portugal and Italy sit at 22.5%, 13.2% and 12.4% respectively.
Merkel, Soros urges, must now save Greece as part of the eurozone by easing its debt burden. "To do otherwise at this stage would create an irreparable split between Europe's rich and poor, and powerful and weak," he wrote.
"The Germans worry about destabilising the euro and bond prices," said Chalmers. "But the Spanish won't sell this to their citizens."