In a report on secret evidence in the UK, Amnesty International
wrote, "Lawyers who spoke with Amnesty International have made it clear that they face profound difficulties in representing their clients effectively where a closed material procedure applies; raising serious questions about how such procedures can achieve any meaningful equality of arms between the parties...The ability of the Special Advocate to effectively represent the interests of the individual where closed material procedures apply is also severely limited. In addition to the effective prohibition on contact with the affected individual once the evidence has been seen, as mentioned above, other reasons given by Special Advocates for this include: the lack of any practical ability to call their own independent witnesses to challenge the government’s case in the closed hearing; the inability to effectively challenge non-disclosure by the government; the admittance of second and third hand hearsay, or even more remote evidence where the primary source is unattributed and unidentifiable making it difficult for that evidence to be properly tested in the closed hearing. These factors have contributed to the overwhelming number of Special Advocates to publicly conclude that closed material procedures “are inherently unfair; they do not ‘work effectively’, nor do they deliver real procedural fairness”.4"
The report went on, "Special Advocates, who can see the secret evidence, have admitted that their ability to challenge the government’s case against an individual is often limited to identifying where allegations made by the Secretary of State might be unsupported by the evidence the government is relying on, or to checking that evidence for inconsistencies, rather than directly refuting or challenging the evidence as they would be able to in ordinary, open proceedings.23"