At some point in the challenge to the ban on Palestine Action beginning on Wednesday, the co-founder of the direct action group will be asked to leave courtroom five at the Royal Courts of Justice, as will her legal team and most others present. Then the case will continue without them. When Huda Ammori returns to the room, the special advocate – a security-cleared barrister – who represented her interests in her absence will not be allowed to tell her or her legal team what evidence was presented against Palestine Action. If Ammori asks what allegations were made directly against her, the special advocate must not tell her, even though that means she will have no chance to rebut them. Such is the nature of the secret courts system, known as the closed material procedure (CMP), within which the legal challenge to the ban will be partly heard. Critics of the system, which can be triggered on an application by a secretary of state, include those who have worked within its strictures. Angus McCullough KC, a special advocate for more than 20 years, said: “CMPs are inherently and unavoidably unfair. The justification for them is that they are the ‘least unfair’ way of dealing with cases in which there is relevant material that genuinely cannot be disclosed to the party affected by it because of its sensitivity and potential to cause harm to the wider public interest, for example, national security, if disclosed.”