There are a number of admissibility criteria that must be satisfied before the Committee begins to consider the merits of an individual communication under the Optional Protocol. These criteria are set out in the Optional Protocol itself and are enshrined in the Committee's jurisprudence. Under the Optional Protocol, the Committee does not have independent fact-finding functions; it only reviews all written information submitted to it by the author of the complaint and the State party concerned. No oral evidence is accepted. The Optional Protocol does not provide a strict rule regarding the distribution of the burden of proof. The Committee generally accepts the facts as presented by the victim if it does not receive any information from the State concerned or if the State only indiscriminately refutes the allegations made. The Committee usually accepts specific refutations by the State of certain facts if the victim is unable to provide documentary evidence to support his own allegations. However, in one case, the Committee recognized that the nature of the complaint may prevent the victim from providing additional evidence and/or that certain information is in some cases exclusively at the disposal of the State party.
In such cases, the burden on the State to refute the alleged victim's allegations becomes heavier.
As a last resort, the State is invited to conduct a good-faith investigation of the applicant's allegations.