What is the test for determining whether a statement is one of opinion or a statement of fact?

This issue was raised by defendant's demurrer but not resolved by the trial court. If defendant's statement is one of opinion, then it cannot be false and is outside the meaning of libel. (Gertz v. Welch, supra, 418 U.S. at 339-340, 94 S.Ct. at 3006-3007, 41 L.Ed.2d at p. 805; see 75 Mich.L.Rev. 1621.) If it is one of fact or one meant to convince the audience it is factual, then it may be within the definition of libel. In its comment to its ruling on defendant's demurrer, the trial court expressly stated that the statement can be interpreted as one of fact or opinion, and if interpreted as a statement of fact, it is libelous on its face. ⁴ The [124 Cal.App.3d 540] issue being one of law and properly raised by the demurrer, the trial court should not have avoided a ruling. (Hurtado v. Superior Court (1974) 11 Cal.3d 574, 579, 114 Cal.Rptr. 106, 522 P.2d 666.) ⁵