In "Stanton v Callaghan" (1999) 2 WLR 745, Chadwick said:  In "Arthur J.S. Hall and Co. v Simons" (2000) UKHL 38, Lord Hoffmann justified the policy in that without the immunity, witnesses "...would be more reluctant to assist the court". In "Darker and others v Chief Constable of West Midlands Police" (2000) 3 WLR 747, the claimant alleged that police officers had conspired with an informant to forge and manipulate records of evidence. Lord Clyde confirmed the immunity for the preparation of a report to be used in court. He said:  This confirms the general principle that a witness does not owe a duty of care to anyone in respect of the evidence given to the court. The only duty is to tell the truth. In Part 35.3 Civil Procedure Rules, the expert’s duty is to help the court and this duty "overrides" any obligation there might be to the client or the person who instructs and/or pays him or her. However, the position in respect of expert witnesses was altered by the decision of the Supreme Court in 2011 in "Jones v Kaney", which overruled "Stanton v Callaghan". As before, an expert will be liable to his client for advice which is tendered to and relied upon by the client under normal principles. However, as a result of the decision, an expert who provides a report which is adduced in evidence before a court no longer enjoys immunity from suit for claims for negligence or breach of contract (although immunity in defamation remains).