He denied being involved, but was charged and sentenced in just 48-hours.
What he and rights groups complained about was the lack of legal information, translation and the chance to organise a defence.
Mann says he thought he was in court to agree to voluntary deportation, without admitting guilt. But instead he found himself in the middle of a quick trial.
He told euronews: “I looked over the interpreter’s shoulder and I could see she’d written something in English, which said ‘leader of the riot, and that’s the first time I knew: that was my charge, leader of a riot.
“And then it was only a minute later that there was a big noise from the crowd, and in Portuguese he’d (the judge) said that I’d been given two years in jail. And then she (the interpreter) wrote it down, and then I realised what I’d got. There was a lot of consternation in the crowd, the English police, and my two witnesses were just sort of ‘what’s going on here, this is crazy’.”
Portuguese authorities have always maintained that Mann’s conviction was legally safe and insisted he serve his jail term.
But with increasing numbers of Europeans travelling, studying and working abroad, a harmonisation of the rules was called for.
New regulations now give all EU citizens the right to translation and interpretation if arrested.
Also, suspects will receive letters that list their basic rights during criminal proceedings, free of legal jargon and in different languages.
Officials in Brussels say at the moment the chance that someone arrested will be properly informed of their rights varies across the European Union.
The attempts to change that are welcomed by rights groups.
Emily Smith, Policy Officer at Fair Trials International, told euronews: “It’s going to be a struggle for governments – or at least a big challenge for governments – to implement these measures. It’s obviously all very well having the laws but you’ve got to see them work in practice.
“But the reality is: there are translation systems available in member states, they do have translators, they do have lawyers, police are charging people with something. And these laws will really focus everyone’s minds on making sure that the police and the judges are trained, to make sure that suspects are given their rights, and get to know what they’ve been charged with, and to understand the proceedings as they’re going on.”
The Netherlands is just one of many countries where legal debate over the issue has been raging for years. Just how can the procedures be improved in a way that is workable and consistent?
Amsterdam police agreed to show us one of their complexes where suspects are kept in holding cells.
Officials here insist that the rights of those arrested are a top priority.
And while the requirement to give written information to suspects will be new in some countries, here things already seem to be advanced.
Arno Portengen, Chief of the Northwest Cell Complex of the Amsterdam Police, showed us an electronic display screen in one of the cells. “This is a terminal, and the detainees can read their rights and the rules in the cellblock. In 24 languages they can read their rights.”
It is also emphasised here that officers who watch over the suspects are not the same as those who carry out the interrogations.
Arno Portengen told Right On: “The law is also for the police and we do everything that we have to do, and we are obliged to maintain the rules. So that’s what we do. If a suspect has the right to see an attorney, we are going to call an attorney or a lawyer.
“Don’t forget that they are suspects. It’s not proven that they have committed a crime. We try to treat them normally, like you would like to be treated. So we respect the law and we have a stated mission and we try to treat the suspects with respect.”
Euronews’ Seamus Kearney reported: “It’s clear that some countries are making more progress than others when it comes to the rights of suspects. But with more than eight million criminal proceedings every year in the European Union, raising standards everywhere is a top priority.”
All members of the EU are signed up to the European Convention on Human Rights, which covers the rights of people accused of a crime. But these new reforms are aimed at strengthening that protection.
Defence lawyers have been campaigning for years to obtain a better set of compulsory safeguards.
Lian Mannheims, the Vice-President of the Dutch Criminal Bar Association, said: “The most important improvement is that the suspect has access to a lawyer at the very first moment, that a lawyer can be consulted before a suspect is interrogated. Because the first phase of criminal proceedings is the most important, and it’s here that the biggest problems usually occur.”
A step-by-step process of achieving common EU standards is already underway.
The first two measures on the Procedural Rights Roadmap have been voted on and adopted, and member states are now required to start implementing the changes.
Still under consideration is the right to a lawyer; the right for suspects to communicate with family members, employers and embassies; and protection for the vulnerable, including children.
But there does seem to be agreement among experts and officials that changing decades of unsatisfactory practices will be difficult.
Theo de Roos, a Dutch appeal court judge & law professor, told Right On: “It is rather easy to formulate rights of citizens, rights of suspects, etc. But then the mentality of police officers, of other officials of criminal procedure, to create open-mindedness, and an inclination to improve the practices, well that’s the big challenge I think.”