Why did Spain's courts rule Catalonia's 2017 independence referendum illegal?
In Catalonia's 2017 vote, 90.18% said Yes, but the turnout was only 43.03%, and Spain's Constitutional Court had suspended the vote beforehand.
Spain's courts ruled it illegal because the Spanish declared the vote unconstitutional on 7 September 2017 and suspended it, after a request from the Spanish government, which said it breached the Spanish Constitution. The referendum, called by the , the Catalan government, went ahead anyway on 1 October 2017. This lesson reports who said what, because the two sides disagree sharply.
The legal fight had two parts. The Catalan parliament approved the vote on 6 September, with 52 anti-independence members boycotting, along with a law saying independence would be binding with a simple majority and no minimum turnout. After being suspended, the referendum law was declared void on 17 October, and the laws were also unconstitutional under Catalonia's , which requires a two-thirds majority, 90 seats, in the Catalan parliament for any change to Catalonia's status.
The result was lopsided and its meaning disputed. The question was "Do you want Catalonia to become an independent state in the form of a republic?" Yes won with 90.18 percent of the votes, but turnout was only 43.03 percent. Catalan government officials argued turnout would have been higher without Spanish police suppression of the vote, and estimated that up to 770,000 votes were not cast because polling stations were closed. On the other side, the constitutional political parties had asked citizens not to take part in what they called an illegal referendum, and most voters who did not support independence did not turn out.
The 2017 Catalan referendum
| Percent | |
|---|---|
| Yes (of votes cast) | 90.2% |
| No (of votes cast) | 7.83% |
| Turnout | 43% |
International observers invited by the Generalitat said the vote failed to meet the minimum international standards for elections, and police action to stop it drew criticism from human rights groups. On 27 October the Catalan Parliament declared independence, and within hours the Spanish Senate approved invoking to assume direct control over some of Catalonia's autonomous powers.
Try it
From turnout and Yes share to a share of everyone registered
y = 0.43x + 0
Challenge · At a turnout of 0.43 and a Yes share of 90, read about 39%. What turnout would turn a 90% Yes into half of all registered voters (about 0.56)?
Quiz me
0/3
Recap
In Catalonia the Yes share was 90.18%, but the vote was ruled illegal and turnout was 43.03%, so the numbers alone could not settle what it meant.
💡 A trick to remember it · Ninety per cent of a minority of the crowd: a big share of a small turnout.
Surprising fact · A law saying independence would be binding on a simple majority was declared void and unconstitutional under Catalonia's own Statute of Autonomy.
Connects to
- ⚖️ Should a referendum need more than half the votes to win?
- 🌾 What did Albertans vote on in the October 2026 referendum on leaving Canada?
- 🗺️ What is secession, and who decides whether a region can leave a country?
- 📜 Did one 1648 peace treaty really invent the modern state?
- 📏 What does "no one is above the law" really mean?
- Referendum
- 2014 scottish independence referendum
Sources (1)
No source, no claim. Every fact in this lesson (15 claims) cites at least one of these.