What follows only applies for major crimes (murder, rape, etc…). There isn’t a jury, an investigation magistrate, and so on for minor crimes or civil cases (with an exception mentioned at the end of the post for particularly complex cases, generally related to finances, embezzlement,… ).
The investigation judge doesn’t take part in the trial. He directs the enquiry, mostly in the way a prosecutor would do in the US system, with the essential difference that he has the duty to seek all the evidences related to the case, elements pointing at guilt as much as elements pointing at innocence (“instruire a charge et a decharge”). He’s supposed to act impartially. One advantage being that the defence must benefit during this investigation phase of the same means as the accusation (like extensive police investigations, for instance).
All the evidences, testimonies, expertises ordered, interrogations, conclusions, etc, are kept in written form. If, at the end of his investigation, he concludes that there are enough charges for a trial, this conclusion is reviewed by a panel of judges who decides whether or not the accused should be tried. The investigation judge then disappear from the picture (actually, he can be called as a witness during the trial, but my understanding is that this usually means that the court suspect he mishandled the case and that he’s in troubles).
The role of the prosecutor is limited during this phase. He appears briefly at the beginning of the investigation, essentially to determine that a crime has occurred (or is likely to have occurred) and for the necessary first investigations. As soon as he has reasons to believe that, yes, this could be a crime, he passes the hand to the investigation judge. After that, in theory at least, he doesn’t have much more say than the defence (for instance, he can request a specific investigation or make recommendation) and in some cases less (for instance, he isn’t present during interrogations).
Still about the prosecution, but regarding the trial phase. A huge difference with the US system is that the prosecutor doesn’t have to prove the case. The court is supposed to determine the truth on the basis on the elements presented, testimonies, etc…, and the prosecutor is only assisting in this discovery, and representing the interest of society. Not only he doesn’t have to prove the case, but he can perfectly argue in favour of the accused or ask the jury to declare him not guilty (of course, it’s very unusual, but it happens). The trial will still keep going on in this situation.
Regarding the trial. I gave several time this comparison : the American system is like a game between the defence and the accusation with the judge as a referee. The French system like a debate on TV with the judge as the anchorman. The presiding judge does much of the interrogation of witnesses. Inadmissibility of evidences is way more limited. For instance, second hand informations or mere opinions can perfectly be expressed.
The accused (or his counsel) is allowed to speak at almost any time, and will frequently be asked questions regarding a testimony following it or even during it, by the judge or the prosecutor, will be allowed to contradict or criticize the testimony, and direct exchanges between the accused and the witness aren’t uncommon. He never formally testifies himself, though, and isn’t allowed to make a sworn statement.
Another notable difference is that the victim (or his family) can also be represented by a lawyer (and generally is).
Regarding the jury (they’re the only ones not allowed to participate in the “debate”, even though they can transmit written questions to the presiding judge, who might or might not ask them to the witness/expert/accused). It’s actually composed of the three judges + the jurors themselves. To declare guilt, a super-majority is required (not unanimity). Sentence is also decided by this jury (judges +jurors).
Basically, the appeal is do-over, exactly similar to the first trial, only with more jurors. It has been added relatively recently, following a decision of the European Court of Human Rights if I’m not mistaken, who considered that the only possible appeal until then, the “cassation” (literally “breaking (of the court decision)”) wasn’t a true appeal, since evidences aren’t reviewed.
The “cassation” still stand as the last appeal. The “cassation” court is the highest court in France for criminal and civil cases (I’m simplifying a bit, since there are other “high courts” for constitutional matters and cases involving public authorities). It doesn’t rule on the facts of the case, but only on the legality of the process (on the “technicalities”, one might say). There are no juror here, only judges. And if they “break” the court decision, a new trial is organized.
There’s an exception though. If new evidences arise, they can be presented to the “cassation” court who can order a new trial. Even though it mellowed a little bit recently, this court has historically been very reluctant to order a new trial, so the new evidences have to be pretty damning. A trivial note : there’s no time limit to present such new evidences. So for instance a dozen years ago, new evidences for a famous case dating back from the 1930s have been presented to the court by the grandchildren or somesuch of the long-dead sentenced murderer (and have been rejected).
Finally : all these informations might not be very useful, because the current president is bent on a major reform of the French system : the suppression of the investigation judge, who would be replaced by a prosecutor (anglo-saxon style). So, all this might be soon outdated.
Note that I’ve a lot of issues with this reform. First it is presented as being intended to protect the accused, in particular following a massive fuck-up by an investigation magistrate who acted as a super-prosecutor in a sordid child rape case that resulted in a random assortment of people who barely avoided sentencing. So, the idea seems to be that since the magistrate who was supposed to be impartial might not be the solution is to replace him by someone who doesn’t have to be impartial at all.
Second, besides major crimes, investigation judges appear also in complex cases, in particular financial cases. And while these judges are independant, the prosecutors, on the other hand, through the hierarchic chain depends ultimately on the minister of justice, hence the executive. So, there are suspicions that they might be strongly “influenced” in cases involving public or political figures.
Third, the french system has a long tradition, there’s a lot of precedents, and so on. This would be a massive change, and without anything to rely upon. It would be entering in uncharted territory. It doesn’t seem a good idea to me.
Fourth, the investigation would become pretty similar to what they are in the American system. The accused would have to face someone with the means of the state behind him and despite promises to reinforce the rights of the defence, I can only envision that a major issue in the american system that I particularly dislike will arise : the means of the accused (an excellent or poor lawyer, a lot of money to spend on private investigations or not, etc…) will become a more important factor, I guess.
Fifth, and this is the biggest issue I have even though it’s rarely mentioned for some reason. The investigation will be conducted in the “american way”, the state against the individual. On the other hand, the trial itself will still be conducted in the “French way”. In particular, as I mentioned, the prosecutor still won’t have to prove the case in court, the admissibility of evidences will be equally extensive, etc… Which means, it seems to me, that the accused will have the worst of both worlds.
It’s not like I’m a specialist of law, so maybe there’s something I’m missing, but the way I see it, I’m infuriated by this proposed reform. I don’t like the French president and his policies at all but if there was one thing I could prevent from happening under his leadership, it’s this one, even though unfortunately, the general public doesn’t seem to feel much concerned about the issue.