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An 'unfavourable' witness is one whose testimony does not advance the case of the party who called him, despite the witness's best intentions. An unfavourable witness must be distinguished from ahostile witness: in general, if a witness proves to be unfavourable, without being hostile, then the party who called him must just take it on the chin. Of course, that party may seek to adduce additional evidence to counteract the testimony of the unfavourable witness; he may also ask the court to give leave for the witness to refresh his memory (WitnessRefreshingMemory). However, he may not attempt to discredit the witness in open court by, for example, asking questions that show the witness's testimony is at odds with his previous statements.