From The Guardian:
The government wants to use secret evidence to counter claims against it. This would undermine the rule of law.
On Monday the House of Lords will consider the government’s proposal for a new system of secret evidence. The closed material procedures (CMPs) would operate in civil proceedings where, for example, an individual brings a case against the government alleging complicity in torture. In defending future cases, the government wishes to be able to place evidence before a judge in the absence of the claimant and his lawyers, invoking a claim that disclosure would “cause harm to national security”.