a presumption is a procedural rule or process by which the existence of fact B may be presumed by proof of the existence of fact A
Some presumptions merely authorize, but do not require, the finder of fact to infer the existence of fact B by proof of the existence of fact A.
2. Permissive Rebuttable Presumption:
in criminal cases, permissible inferences may also be called permissive rebuttable presumptions. When a permissive rebuttable presumption exists, the finder of fact may accept or reject the inference the existence of the presumed fact. The presumption is rebuttable because the opposing party has the right to introduce evidence that rebuts the presumption. This rebuttal evidence may either challenge the existence of fact A, may challenge the validity of the inference that leads to fact B, or may challenge the exists of fact B.
1. Mandatory Presumptions Generally:
When the law establishes a mandatory presumption, upon the proof of fact A, the trier of fact must presume the existence of fact B. Mandatory presumptions, especially those in criminal trials, are subject to constitutional scrutiny.
2. Conclusive Presumptions:
When a presumption is not subject to rebuttal, that presumption is described as conclusive. Conclusive presumptions are subject to due process and equal protection considerations.