The Act - Commentary on Sections Part 3 – Trial and Punishment of Offences Section 24: Offences in relation to courts-martial etc.
85.The SDAs make it an offence for anyone subject to Service law to refuse “to produce any document in his custody or control which a court-martial has lawfully required him to produce” (for example, section 57(1)(c) of the Army Act 1955). Section 24 of this Act extends this, so that a refusal to produce other things that are likely to be material evidence is also an offence.
86.The SDAs include similar provisions (for example, section 101(1)(c) of the Army Act 1955) in relation to persons not subject to Service law. If such a person refuses to produce a document when required to do so by a court martial, then the court-martial may certify that as a contempt, to be dealt with by the civilian courts. Section 24 extends this to apply to the refusal to produce other things as well as documents.