The key legal question and the source of law 

The principal issue raised by the concerned appeals is whether a conviction based “solely or to a decisive extent” on the statement of a witness whom the defendant has had no chance of cross-examining necessarily infringes the defendant’s right to a fair trial under Article 6(1) and 6(3)(d) which provide:

“(1) In the determination of his/her civil rights and obligations or of any criminal charge against him/her, everyone is entitled to a fair and public hearing within a reasonable time by an independent and impartial tribunal established by law....
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(3) Everyone charged with a criminal offence has the following minimum rights:
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(d) to examine or have examined witnesses against him and to obtain the attendance and examination of witnesses on his behalf under the same conditions as witnesses against him.".