Al-Saadoon & Others -v- the Secretary of State for Defence  EWHC 773 (Admin).
Witness statements must contain the truth, the whole truth and nothing but the truth on the issues covered. Great care must be taken in the preparation of witness statements. No pressure of any kind should be placed on a witness to give other than a true and complete account of his or her evidence. It is improper to serve a witness statement which is known to be false or which the maker does not in all respects actually believe to be true. In addition, a professional adviser may be under an obligation to check where practicable the truth of facts stated in a witness statement if he or she is put on enquiry as to their truth. If a party discovers that a witness statement which they have served is incorrect they must inform the other parties immediately.