A majority of voters in Catalonia elected to secede from Spain last month. The catch? The vote was unofficial. Some 81 percent of Catalonians voted in favor of the move.

On a legal level, Catalonia’s regional parliament approved a plan to begin separating from Spain by 2017. That move defies Madrid’s assertions that doing so violates Spain’s constitution. The Catalonian government, based in Barcelona, approved the motion in November by 72 votes to 63. The resolution declared “the start of a process toward the creation of an independent Catalan state in the form of a republic” and a “process of democratic disconnection not subject to the decisions by the institutions of the Spanish state.”

Catalonian citizens turned out in huge numbers for the unofficial vote, which was organized by 4,000 volunteers. Technically, the vote was held in violation of Spanish law, but that didn’t deter the 2.25 million people — about half the region’s eligible voters — who turned out. Catalonia has held similar votes, more than a dozen, in the past few years, but this one has been the biggest.

Spain’s government quickly released a statement in opposition to the move, downplaying its significance: “Catalonia is not going anywhere. Nothing is going to break,” said Spanish Prime Minister Mariano Rajoy, who pledged to halt the movement.