I think ECHR will take Knox's case because it does raise a generic issue they will wish to address. Mignini decided to restrict Sollecito's and Knox's access to lawyers until immediately before their first court appearance. Mach tells us that Mignini is allowed to do this under Italian law, I believe him.
The issue is that under ECHR rulings, this should not be permissable, it is an example of how Italy has not integrated European Human Rights into the Italian legal system. I think their view will be that although the PM can restrict access to a lawyer for upto 48 hours, this should be exceptional, not routine or arbitrary. In the UK a police officer of superintendent rank or above can restrict access to lawyer of a suspect, but the grounds are restricted, and the basis for any such decision has to be documented, and can be subsequently challenged.
So I think that the ECHR will rule that Italy has to restrict the grounds on which the PM can restrict access to a lawyer of a suspect, and that the grounds should be documented. This was not done. What I am uncertain of is when they will say that Knox became entitled to a lawyer. The ECHR seem to take a pragmatic approach, that the circumstances define the right not an arbitrary documentation. In the latter case, this enables investigatory authorities lee way to exploit legal loop holes. ECHR seem to say that it is not just to use a legal loop hole to evade access to counsel for a suspect.
I am certain they will take the view that Mignini as a lawyer should have recognised Knox's right to a lawyer prior to his taking a 'spontaneous' statement. I am less certain of whether they will take the view that prior to the first statement she became a suspect. My personal view is this certainly became true when she made a verbal statement and prior to her first written statement.
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The formal definition of when Ms. Knox became a "suspect" may not be as relevant as simply the fact that she was being interrogated without a lawyer. The planning for the interrogation by the police, and the fact that Knox was "invited" into an interrogation room to answer a few questions and clear up some alleged "contradictions" in her previous statements to police means that she was the equivalent of a suspect, with no right to leave the situation without legal consequences. Judge Raimondi and 7 other judges of the ECHR have pointed out this obligation of a witness or suspect to obey police and not leave in a concurring opinion in another case which I have posted, CREANGĂ v. ROMANIA 29226/03 23/02/2012.