Yes they did, as did all signatories to the Convention. And contrary to Vixen's semi-literate understanding of the situation, the ECHR absolutely DOES have the power to intervene in the affairs of a state, provided that the state is a signatory to the Convention. The ECHR acts as a supra-national court whose judgements and orders are absolutely binding upon the signatory states.
It's an often-parroted pro-guilt canard that the ECHR cannot overturn convictions. And while this is absolutely correct (in our case, for example, the ECHR cannot and will not tell Italy to annul Knox's criminal slander conviction), the ECHR can and does order signatory states to apply full and proper remedies to restore an individual's human rights. Clearly, if a conviction is significantly based on something that infringed the person's human rights, the very finding of the human rights breach by the ECHR makes the conviction, by definition, unsafe at the very least.
In some instances, it may be fair and appropriate to conduct a retrial of the person. For example, suppose that Mr A was accused of killing a man in a bar, and there was a good amount of eyewitness testimony that Mr A was the killer, but Mr A was unlawfully coerced into confessing, it's probably correct to retry Mr A without the now-discarded confession, to see whether the eyewitness testimony on its own will be sufficient in the eyes of a court to prove guilt beyond reasonable doubt. Likewise, if the ECHR rules that even though a person's human rights were breached, the breach wouldn't have had a material effect upon the conviction, it may be fair and acceptable to retain the conviction without any retrial (e.g. a man with a genuine mountain of reliable, credible evidence of his guilt of the crime who was unlawfully denied access to a lawyer during his first interrogation as a suspect).
But in the Knox case, the human rights breach under discussion is, in effect, the entire genesis of the crime for which she was convicted (i.e. the criminal slander). If when the the ECHR rules that Knox was unlawfully coerced into accusing Lumumba, and that she was unlawfully questioned as a "witness" long after she clearly should have been declared a suspect and afforded the appropriate rights and protections, the entire evidence base for the criminal slander conviction disappears into thin air. So in the Knox case, once the ECHR rules in Knox's favour, it will order Italy to apply full remedy to restore Knox's human rights and to compensate her for the breach. And the ONLY course of action open to Italy in this scenario will be to annul the criminal slander conviction without retrial (since there will now be zero usable evidence against Knox in respect of the criminal slander), and to pay her a large sum of money by way of compensation.
So no, the ECHR cannot (and will not) order Italy to quash Knox's criminal slander conviction. But in practice, the ECHR (by means of its judgement and ordering of a full remedy) will place Italy in a position where it has no choice but to quash the conviction.
