A reason alleged for the doing or not doing a thing. This word presents two ideas differing essentially from each other. In one case an excuse may be made in, order to own that the party accused is not guilty; in another, by showing that though guilty, he is less so, than he appears to be. Take, for example, the case of a sheriff who has an execution against an individual, and who in performance of his duty, arrests him; in an action by the defendant against the sheriff, the latter may prove the facts, and this shall be a sufficient excuse for him: this is an excuse of the first kind, or a complete justification; the sheriff was guilty of no offence. But suppose, secondly, that the sheriff has an execution against Paul, and by mistake, and without any malicious design, be arrests Peter instead of Paul; the fact of his having the execution against Paul and the mistake being made, will not justify the sheriff, but it will extenuate and excuse his conduct, and this will be an excuse of the second kind. 3. Persons are sometimes excused for the commission of acts, which ordinarily are crimes, either because they had no intention of doing wrong, or because they had no power of judging, and therefore had no criminal will; or having power, of judging they had no choice, and were compelled by necessity. Among the first class may be placed infants under the age of discretion, lunatics, and married women committing an offence in the presence of their husbands, not malum in se, as treason or murder; or in offences relating to the domestic concern or management of the house, as the keeping of a bawdy house. Among acts of the second kind may be classed, the beating or killing another in self-defence; the destruction of property in order to prevent a more serious calamity, as the tearing down of a house on fire, to prevent its spreading to the neighboring property, and the like.