The directive, which was first tabled by the European Commission in July 2009, aims to set EU-wide minimum standards giving citizens the right to receive interpretation and translation in their native language in criminal cases across the European Union.
The MEPs backed the draft text, which is intended to improve the rights of suspects or accused persons who do not understand the language of proceedings, by a huge majority of 637 votes to 21 yesterday.
The directive can now pass into EU law as it has already been approved by member states in the Council of Ministers.
Yesterday's text must still be formally adopted by governments in the Council as stipulated by the Lisbon Treaty's co-decision provisions, but this is considered a procedural formality after justice ministers backed the draft directive on 4 June.
UK Liberal Democrat MEP Sarah Ludford, whose role as the European Parliament's rapporteur on the directive saw her conduct negotiations with the Spanish EU Presidency, hailed the adoption of the new rules as "a genuinely historic event" and a "leap forward for European justice".
It will "strengthen fair trial rights and equality of procedural rights throughout the EU," she said. "What the Parliament voted for today is effective, efficient and transparent justice. Now it is for member states to make it happen," she added.
The new law ensures that people suspected of having committed a crime on EU soil will receive written translations of all essential documents - including the detention order, charge sheet and indictment - when facing trial outside of their country of residence, rather than having to rely upon oral translations summarising the evidence.
Under the new rules, not only will interpretation have to be provided at trial, but also for communication with lawyers and during investigations, including police questioning.
The accused must have access to interpretation and translation in his/her native language during all phases of criminal proceedings "of every kind," from the time he/she is made aware that he is suspected or accused of committing a criminal offence until all appeals are exhausted and including questioning, pre-trial, sentencing and detention.
When it is impossible for interpreters to attend in person, videoconferencing, telephone or Internet can be used "unless the physical presence of the interpreter is required in order to safeguard the fairness of the proceedings," the Parliament said.
Costs to be borne by member states
The cost of providing such services will be borne by the EU country in which the accused is standing trial rather than by the suspect.
"Any extra costs that the directive will impose on member states are the irreducible cost of ensuring fair trials and avoiding miscarriages of justice and will in any case be balanced by fewer costly appeals and delays," said Parliament rapporteur Ludford.
"Cutting corners on costs is not best value since if you get a poor court decision or bad police practice, then people are going to appeal," she said.
Moreover, the law stipulates that before waiving their right to interpretation and translation, citizens must be given the chance to speak to a lawyer.
The same rights will be offered to persons subject to a European Arrest Warrant, as well as people with hearing or speech impediments.
"It is the first – and an overdue – EU measure on fair trials to go alongside the European Arrest Warrant and also the first EU criminal justice legislation to be negotiated under co-decision with MEPs rather than decided by national ministers alone," said Ludford.
Denmark will not adopt the legislation as it does not take part in any EU initiatives on criminal justice.
The EU's other 26 governments have three years to transpose the directive into national law.