Is it true that European courts didn't allow the accused to know the evidence used against them?

I am currently conducting some work in a courthouse preserved exactly how it was from 1830 and replacing the previous courts that were previously on the site. I have focused so far entirely on English law, and this is the first I have heard of European Courts conducting trials in this way, so super question! Since you asked specifically about whether the English Courts operated like this I do feel my answer will still be relevant to what you want to know. So far as my research has taken me from the early medieval period to pretty much the present day the role of the courts was conducted very much in public. Really the antithesis of the situation you have described. This is partially due to the fact that English law (particularly common law) has evolved (sort of) from first Roman law. The Romans took publicity VERY seriously. Cicero, the famous orator would have operated as a lawyer very much in the public sphere and it was considered a reasonable form of entertainment, if there was nothing good on the Circus Maximus or theatre, that you would head down to the law courts. This meant that the law was dispensed in front of a public audience who would appreciate the oratory skill and legal knowledge of the famous advocates. This famous example can be read in full here

After the last oration it was decided that Cicero was to conduct the prosecution against Verres; accordingly, a hundred and ten days were allowed to him to prepare the evidence, with which object he went himself to Sicily to examine witnesses, and to collect facts in support of his charges… abandoned his idea of making a long speech, and of taking up time in dilating on and enforcing the different counts of the indictment, and resolved to do nothing more than produce his witnesses, and offer them to examination; and this novel method of conducting the case, together with the powerful evidence produced, which he could not invalidate, so confounded Hortensius, that he could find nothing to say in his client's defence, who in despair went of his own accord into banishment. Cicero, in Verrem (English) 1.1

This precedent of law is important, because I believe that while it would be foolish to see the way law was conducted in Roman times as a direct translation forward. We also have to consider the influence of later invaders and their own means of justice. Certainly the Vikings had an influence, especially in the north of England. The form of legal administrative region, the Wapentake, has only really just been phased out in the administrative organisation of Yorkshire in the previous century. The Old Bailey also has kept meticulous archives of the court material from 1674. All of which can be accessed online

This leads me on to a perhaps the most salient point; unlike today, law in all its forms was not separated out into different disciplines. Criminal, family and administrative decisions, especially in areas further form the capital were conducted by the same group of upstanding members of the community. The only (very much imperfect) comparison I can think of is supreme courts who have to rule on anything as the highest court of appeal, from criminal cases to legislative reviews. The local magistrates court that I am researching replaced a much less formal set up. The court was overseen by magistrates and were responsible for everything from the upkeep of highways in their jurisdiction to issuing licences for public houses, as well as any criminal cases. They simply did not have the time to mess around with secret evidence. Everything was voiced in the open, often in front of a sizable assembled crowd. In fact the courts were so public that in Leeds (Yorkshire, North England) the court had been traditionally held by an oak tree on the outskirts of the city before suitable premises were decided upon as more appropriate. Before the courtroom was established courts were held in any building suitable enough to hold the numbers of people required for a case. By that very fact it made them very much public affairs.

I have rambled on so please ask if there isn’t something I covered. See below for some excellent sources:

Romans: Cicero. Pro Caelio. In Cicero: Defense Speeches: Oxford World Classics. Edited and Translated by D. H. Berry. New York: Oxford University Press, 2000

The Old Bailey: Voices from the Old Bailey, a radio documentary by Dr. Amanda Vickery