“Let’s suppose there was a tapped phone call in the course of which somebody, perhaps even the dangerous criminal with whom Gaglione apparently came to blows, explicitly claims responsibility for the murder. Let’s imagine that this call is unusable for a variety of procedural reasons. If we considered the criterion of unusability to be absolute and completely unchallengeable, we would have to ignore that conversation, even if it proved Cardace’s innocence, and confirm the original ruling.261

“Does this strike you as an acceptable hypothesis or, on the contrary, do you see it in all its frightening absurdity?

“In reality, I believe that unusability is a sanction intended to protect suspects and defendants. Tapped phone calls that are unusable can’t be used against somebody, but they can, and in my opinion must, be used whenever they contain elements that clear a suspect; this in accordance with the two principles I spoke about earlier, favor rei and favor libertatis, in other words the general rules of the whole system, in the light of which individual rules should be interpreted.

“If a testimony about a common rumour, in theory forbidden, offers the prospect of an alternative explanation of the facts of a case, if an indirect statement about a common rumour opens the way to reasonable doubt, which is the cornerstone of the system, the principle of unusability must be overruled and the judges allowed to decide for themselves.”

I paused, hoping that I’d got my message across. Because I didn’t even believe in this argument myself.

I’d made a leap in logic. There was a significant difference between my example of the tapped phone conversation clearing an innocent man and Rafaschieri’s testimony about a rumour.

In a hypothetical case like the one I had formulated, any judge, although there might be different nuances in his ruling, would admit the tapped conversation and acquit the defendant. He would do so anyway, however objectively complex the case was to interpret. Any judge would find a way to acquit, because there would be no doubt about the veracity and validity of that conversation, even if the procedure by which it had been obtained was flawed.

The rules on the unusability of phone-tap evidence protects suspects from unlawful procedures. The rule that 262prohibits testimony about rumours protects against the introduction of information that’s completely impossible to check and verify. It would be all too easy to weaken or demolish a prosecution case if you could call witnesses who, to give an example, claimed to provide an alibi by saying they had heard a rumour, that everyone was saying it, that it was common knowledge.