At common law, children were generally regarded as incapable of committing crimes. However, different presumptions have generally been applied, depending upon the age of the child. Generally, it is conclusively presumed that a child under the age of seven is unable to form a criminal mens rea and, therefore, a child that young cannot be convicted of a crime. Children between the ages of seven and fourteen are also presumed incapable of forming criminal mens rea. However, this presumption is rebuttable. Therefore, even though the law leans away from convicting children between the ages of seven and fourteen, the prosecution can still obtain a conviction by proving that the child knew what he was doing and knew that what he was doing was wrong. However, this rebuttable presumption does not apply to the crime of rape. Simply stated, a male child under the age of fourteen is conclusively presumed to be incapable of committing rape.
Many jurisdictions still abide by the common law in their treatment of children. However, certain jurisdictions have departed from the common law and have raised the minimum age for criminal liability while other jurisdictions have eliminated the conclusive presumption for children under the age of seven and have extended the rebuttable presumption of incapacity to all age groups including children under the age of seven.
According to both the common law and modern statutes, the child’s age will be determined by how old he is when he commits the crime, and not how old he is at the time of the trial. See
In addition, the child’s actual age rather than his mental age will control. In other words a fifteen year old child who only has the mental capacities of a four year old will be treated as a fifteen-year-old and not as a four-year-old.