The strict home lockdown, ordered to control the spread of the coronavirus during Spain's first state of alarm, was unconstitutional a top court has ruled - by six votes in favour and five against.

In a historic judgement the Constitutional Court has decided that the government of Prime Minister Pedro Sánchez suspended fundamental rights rather than just bringing in a limitation of them, as allowed by the state of alarm.

In March 2020 Sánchez declared an "estado de alarma" which is a milder form of state of emergency within the Spanish Constitution.

The strict lockdown, when citizens were only allowed to leave their homes for essential reasons for several weeks, would only have been legal under the umbrella of the higher level of emergency, known as an "estado de excepción", said the court on Wednesday.

The court ruling could open the door to a wave of possible lawsuits and the annulment of many of the 1.2 million fines issued during the time that the order lasted.

After three weeks of intense deliberations, which began on 22 June, it was the vote of the vice-president of the court, Encarnación Roca, that swung the balance and saw the court rule in favour of declaring the mass lockdown during the first-wave of the pandemic to be unconstitutional.

Sources close to the court explained that the law that regulates an "estado de alarma" empowers the Government to "limit" the movement or stay of people or vehicles "at certain times and places", but not impose a general ban on movement such as the one established by the Sánchez government in March 2020. A measure of such significance, according to the Court, is a full-blown suspension of fundamental rights.

The strict home lockdown that the Constitutional Court considers illegal was in effect for exactly 50 days, between 14 March and 4 May, 2020. From that date onward the central government gradually allowed some freedoms (to do exercise and walk with household members) although the restrictions on movement continued until the state of alarm ended on 21 June.

This Constitutional Court ruling will now set the limits for future states of alarm, since never before has it been tested in the courts.

Only once, before the pandemic, during the air traffic control crisis of 2010, had the state of alarm mechanism been activated.