Unlawful Evidence: the Fruit of the Poisonous Tree in Spain (2026)

Unlawful evidence is one of the most powerful concepts in criminal defence: evidence obtained by breaching fundamental rights cannot be used to convict. As criminal lawyers, we explain its scope.

What Article 11.1 of the Judiciary Act Says

Article 11.1 of the Organic Law of the Judiciary provides that evidence obtained, directly or indirectly, by breaching fundamental rights or freedoms shall have no effect. The consequence is that such evidence is null and cannot be assessed.

The Fruit of the Poisonous Tree

The fruit of the poisonous tree doctrine extends the nullity: if the original evidence is unlawful, the derived evidence is also tainted. If a void search leads to finding a weapon, that find may also be excluded. The key is the connection of unlawfulness between the unlawful evidence and the derived one.

The Exceptions to Nullity

• Independent source: the evidence would have been obtained by another lawful route.
• Inevitable discovery: the find would have happened anyway.
• Chance discovery: an unsought find during a lawful operation.
• Voluntary later confession, with legal assistance, that breaks the chain.

The Role of the Defence

A rigorous defence examines how each piece of evidence was obtained: the lawfulness of searches, wiretaps and arrests. If the essential evidence is unlawful, the prosecution may be left without support.