Scotland's First Minister yesterday named the date she would like another referendum on independence to take place - October 19, 2023.
But there are hurdles to jump before Nicola Sturgeon gets her way.
She said the question would be the same as in the last referendum in 2014: "Should Scotland be an independent country?"
Ms Sturgeon has written to Prime Minister Boris Johnson to ask for formal consent for the vote to be held.
She said she would press on with her plan if this was not granted by the UK Government.
But she stressed that any referendum would need to be "indisputably lawful" and constitutional - with the Supreme Court now being asked to rule on whether the Scottish Government has the power to hold a vote without UK Government approval.
Ms Sturgeon said Scotland's top law officer, the Lord Advocate, had referred the case to the UK's highest court, with court papers being served on UK Government law officers on Tuesday afternoon.
Supreme Court
Next, the president of the Supreme Court will decide if there are preliminary matters to be addressed and when the case will be heard.
The first minister said she hoped the court would be able to "deliver clarity and legal certainty in a timely manner" instead of MSPs passing the bill only for it to subsequently face a legal challenge from opponents.
If the court rules that Holyrood does not have the power to hold a referendum, she said the next general election would become a "de facto referendum" with the SNP standing on a single issue of independence.
The BBC says the UK Government stated it would examine the first minister's proposals, but stressed that its position that "now is not the time" for another referendum had not changed. It has also said that it is "clear" that the constitution is reserved to Westminster.
Douglas Ross, the leader of the Scottish Conservatives, said another referendum was the "wrong priority for Scotland" and would hinder Scotland's recovery from the pandemic.
He accused the first minster of "railroading" parliament into talking about the SNP's "obsession" with another independence vote.
"We won't take part in a pretend poll when there is real work to be done," Mr Ross said.
Top priority
Scottish Labour leader Anas Sarwar said the SNP had asked people to vote for them in the last Scottish Parliament election on the basis that Covid recovery would be the party's top priority.
He said: "Isn't it the case that the 'Pandemic Nicola' that said she wanted to pull us through is gone and the 'Partisan Nicola Sturgeon' that wants to divide our country is back pursuing a referendum that two-thirds of Scots don't want right now?
Alex Cole-Hamilton, of the Scottish Liberal Democrats, said the first minister's statement was an "appalling waste of energy and focus", and that Ms Sturgeon's "fixation with breaking up the country will always trump the needs of the people that we are all here to serve".
Meanwhile, MSPs have voted to make some emergency Covid-19 powers permanent, including the ability to impose lockdowns and close schools.
As well as measures affecting the education and justice systems the new legislation also makes it harder for tenants to be evicted.
But the BBC says opposition politicians said the bill amounted to a "power grab".
MSPs took five hours to debate more than 90 amendments to the Coronavirus (Recovery and Reform) Bill before passing it by 66 votes to 52.