Separatists in the wealthy, northeastern region have for years tried – in vain – to win approval from Spain's central government to hold an independence vote like Scotland's 2014 referendum on independence from Britain which resulted in a “no” vote.
Catalan President Carles Puigdemont pledged in the autumn to hold such a referendum in September 2017, whether or not the central government in Madrid agreed, and the majority-separatist, regional parliament subsequently approved his plan.
The court said in a statement it “suspends… the resolution of Catalonia's parliament that plans a referendum in 2017”.
It also warned Catalan politicians involved in the process, such as parliament speaker Carme Forcadell and Puigdemont, that they had a duty to “stop or paralyse” any move to ignore or dodge the suspension, or face “potential liabilities, including at a penal level”.
Catalonia's former president Artur Mas had already tried to hold such a referendum, but it was banned by the Constitutional Court so he held a symbolic, non-binding independence vote instead in November 2014.
More than 80 percent cast their ballot in favour of independence then – although just 2.3 million people out of a total of 6.3 million eligible voters took part.
Artur Mas is due to stand trial for staging a symbolic vote. Photo: AFP
But Mas is now due to stand trial for staging the vote on charges of serious disobedience and malfeasance, and risks a 10-year ban on holding public office.
In this latest attempt, the Constitutional Court has five months to decide whether to implement the suspension for good, or lift it.
But it is highly unlikely to allow the vote to go ahead, given that it ruled in 2014 that, under the constitution, no region can unilaterally call an independence referendum that will affect the entire country.
Catalans have nurtured a separate identity for centuries, with their own language and customs.
Their long-standing demands for greater autonomy have been exacerbated by Spain's recent economic downturn, leaving many resenting the amount of taxes they pay to the central government in Madrid to subsidise poorer regions.
Calls for outright independence have increased in recent years, and polls show Catalonia, which accounts for almost a fifth of Spanish economic output, is roughly divided in half over splitting from Spain.