Turncoat witness is a witness whom the litigating party calls to provide favorable testimony but during the trial they become a hostile witness.
For example, in People v. Brown, a California Court of Appeals case, a witness told her mother, doctor, friends, and police officers that the defendant beat and kicked her. Later, at trial, the witness changed her story and claimed that she was the aggressor and then became injured during her attack on the defendant.
Evidentiary rules protect the surprised litigant’s ability to expose the turncoat witness’s inconsistency. Federal Rule of Evidence 607 allows any party, including the litigant who called the witness, to attack the witness’s credibility. Also, as Brown described, California Evidence Code § 1235 protects a party against turncoat witnesses by permitting the admission of prior inconsistent statements to attack that witness’s credibility.
[Last updated in November of 2021 by the Wex Definitions Team]