What is a defendant's right to present his own witnesses in his own defense?

"The right to offer the testimony of witnesses, and to compel their attendance, if necessary, is in plain terms the right to present a defense, the right to present the defendant's version of the facts as well as the prosecution's to the jury so it may decide where the truth lies. Just as an accused has the right to confront the prosecution's witnesses for the purpose of challenging their testimony, he has the right to present his own witnesses to establish a defense. This right is a fundamental element of due process of law." (Id., at p. 19, 87 S.Ct. at 1923; see also Chambers v. Mississippi (1973) 410 U.S. 284, 302, 93 S.Ct. 1038, 1049, 35 L.Ed.2d 297; ("Few rights are [157 Cal.App.3d 591] more fundamental than that of an accused to present witnesses in his own defense.").)