What is the effect of immunity for a police officer testifying on the witness stand?

Briscoe v. LaHue primarily addresses the policy concerns underlying witnesses' testimony, with protection from fear of subsequent suit being the means to encourage witnesses to come forward to testify, and to testify candidly. (460 U.S. at pp. 332-334, 103 S.Ct. at pp. 1113-1115.) The court observes, in this connection, that "[a] police officer on the witness stand performs the same functions as any other witness; he is subject to compulsory process, takes an oath, responds to questions on direct examination and cross-examination, and may be prosecuted subsequently for perjury." (460 U.S. at p. 342, 103 S.Ct. at p. 1119.) Accordingly, police officer witnesses are entitled to the same immunity enjoyed by other witnesses. (460 U.S. at pp. 345-346, 103 S.Ct. at pp. 1120-1121.)