Legal Definitions - mandatory presumption

A mandatory presumption (also known as a conclusive presumption) is a legal rule that requires a judge or jury to accept a certain fact as true once another set of foundational facts has been proven. Unlike other types of presumptions, a mandatory presumption cannot be challenged or disproven by presenting evidence to the contrary. Once the triggering facts are established, the presumed fact is treated as an undeniable truth in the eyes of the law.

• Example 1: Criminal Capacity of Minors

  In some legal systems, a child below a specific age (for instance, seven years old) is legally presumed to lack the mental capacity to form criminal intent. If a six-year-old child commits an act that would otherwise be considered a crime, the law *mandatorily presumes* that the child could not have intended to commit a crime. No amount of evidence suggesting the child understood the wrongfulness of their actions could overcome this presumption; the court must accept that the child lacked criminal intent, and therefore cannot be held criminally responsible.

• Example 2: Acceptance of Contract Terms by Signature

  When an adult signs a legally binding contract, they are often conclusively presumed to have read, understood, and agreed to all the terms and conditions contained within that document. For instance, if an individual signs a complex software licensing agreement, they cannot later claim in court that they didn't read or comprehend a particular clause to avoid its obligations. The act of signing triggers a *mandatory presumption* that they assented to all terms, and this presumption cannot be rebutted by simply asserting ignorance or lack of understanding.

• Example 3: Adverse Possession After Statutory Period

  In property law, if someone openly, notoriously, continuously, and adversely occupies another person's land for a period defined by statute (e.g., 20 years), the law in some jurisdictions *mandatorily presumes* that the adverse possessor has acquired legal title to the property. If, after 25 years, a person has met all the requirements for adverse possession, the original owner cannot suddenly appear and claim the land back. Once the statutory period has passed and the conditions are met, the law *mandatorily presumes* the adverse possessor is the rightful owner, and this presumption cannot be overturned by the original owner simply asserting their prior ownership.