In ECHR case-law, such as Gafgen v. Germany [GC] 22978/05 June 1, 2010 and more recently in Lyapin v. Russia 46956/09 July 24, 2014, the ECHR has found that:
The Court has considered treatment to be “inhuman” because, inter alia, it was premeditated, was applied for hours at a stretch and caused either actual bodily injury or intense physical and mental suffering. Treatment has been held to be “degrading” when it was such as to arouse in its victims feelings of fear, anguish and inferiority capable of humiliating and debasing them and possibly breaking their physical or psychological resistance, or when it was such as to drive the victim to act against his will or conscience (see Gäfgen, cited above, § 89).
Applying the concept in the judgment to the interrogations of Amanda Knox and Raffaele Sollecito on the night of November 5/6, 2007, there are the following parallels:
1. The treatment was premeditated: there was a contingent of police in the station, and according to the testimony of Director Giobbi of the SCO Police Unit, he had planned interrogations of both individuals to be held simultaneously.
2. The treatment apparently caused intense mental suffering in the individuals.
3. The treatment undoubtedly aroused in the victims feelings of fear, anguish, and inferiority that was capable of, and indeed succeeded, in breaking their psychological resistance, as evidenced by their confusion and the obviously false statements that the police induced both of them to sign.
A consequence of the ECHR finding that an individual has been subjected to degrading treatment is that any conviction resulting directly from information gained from the individual as a result of the degrading treatment is considered unfair, a violation of Convention Article 6. Thus, typically, the State that has committed the violation must redress it, by, for example, retrying the individual if he/she requests, but only using information and procedures in conformity with Article 6.
For Amanda, this means that, assuming the ECHR agrees that there was degrading treatment, the conviction for calunnia cannot stand.
In addition, of course, is the Salduz v. Turkey case-law relating to conviction for statements made under interrogation without a lawyer. Application of those precedents gives the same result, that Amanda Knox's conviction for calunnia was unfair and any retrial must be held in conformance with Article 6. Since the calunnia "crime" is merely a series of statements, perhaps including in the opinion of the Italian courts the written Memoriales, all of which were the product of an interrogation without a lawyer and/or police custody without a lawyer, the statements and Memoriales are not usable for conviction and thus the entire case vanishes. Of course, it may vanish as out of time allowed by the statute of limitations as well.