People v. McCall

In People v. McCall (2004) 32 Cal.4th 175, the California Supreme Court summarized the difference between "permissive" and "mandatory rebuttable presumptions" on the one hand, and "conclusive presumptions" on the other. (Id. at pp. 182, 184.) The McCall court explained that a presumption "'is an assumption of an ultimate or elemental fact . . . to be made from an evidentiary or basic fact or group of such facts found or otherwise established in the action.'" (Id. at p. 182, quoting Evid. Code, 600, subd. (a), brackets added in McCall.) A permissive rebuttable presumption exists when a fact finder may find an elemental fact based on the proof of a basic fact. (McCall, supra, 32 Cal.4th at p. 183.) A mandatory rebuttable presumption exists when a fact finder must find the elemental fact where the basic fact is established. (Ibid.) In either case, "the defendant has the opportunity to rebut the presumed connection between the basic and ultimate facts." (Ibid.) The McCall court noted that a mandatory rebuttable presumption may be unconstitutional: "Because a mandatory rebuttable presumption 'tells the trier of fact that he or they must find the elemental fact upon proof of the basic fact, at least until the defendant has come forward with some evidence to rebut the presumed connection between the two facts,' it is a 'troublesome' evidentiary device in a criminal case since the prosecution bears the burden of establishing guilt beyond a reasonable doubt. The prosecution 'may not rest its case entirely on a mandatory rebuttable presumption unless the fact proved is sufficient to support the inference of guilt beyond a reasonable doubt.'" (McCall, supra, 32 Cal.4th at p. 182.) In contrast to permissive and mandatory rebuttable presumptions, conclusive presumptions "are irrebuttable by definition . . . ." (McCall, supra, 32 Cal.4th at p. 185, citing Evid. Code, 620.) "'A conclusive or indisputable presumption is entirely different from the ordinary rebuttable presumption: No evidence may be received to contradict it. Hence, it is more accurately described as a rule of substantive law rather than of evidence." (McCall, supra, 32 Cal.4th at p. 185.) Because a conclusive presumption "simply describes a legislative enactment of substantive law" (id. at p. 187), it does not pose the constitutional concerns present in a statute that contains a mandatory rebuttable presumption. (Id. at p. 185 "Our court has repeatedly rejected defendants' attempts to invoke the term conclusive presumption as a means to challenge the constitutionality of criminal law statutes".)