(a) The use of physical force by an actor upon another person is justifiable when the actor is a parent, guardian or other person entrusted with the care and supervision of a minor or an incompetent person or when the actor is a teacher or other person entrusted with the care and supervision of a minor for a special purpose; and

    (1)    The actor reasonably believes that the force used is necessary to promote the welfare of a minor or incompetent person, or, if the actor's responsibility for the minor is for special purposes, to further that special purpose or to maintain reasonable discipline in a school, class or other group; and

    (2)    The force used is not designed to cause or believed to create a substantial risk of causing death, serious physical injury, disfigurement, extreme pain or extreme emotional distress.

    (b) The use of physical force by an actor upon another person is justifiable when the actor is a person responsible for the operation of or the maintenance of order in a vehicle or other carrier of passengers and the actor reasonably believes that such force is necessary to prevent interference with its operation or to maintain order in the vehicle or other carrier, except that deadly force may not be used unless the use of deadly force is authorized by state and federal law.

    (c) The use of physical force by an actor upon another person is justified when the actor is a physician or a person assisting at his direction; and

    (1)    The force is used for the purpose of administering a medically acceptable form of treatment which the actor reasonably believes to be adapted to promoting the physical or mental health of the patient; and

    (2)    The treatment is administered with the consent of the patient or, if the patient is a minor or an incompetent person, with the consent of the parent, guardian, or other person legally competent to consent on his behalf, or the treatment is administered in an emergency when the actor reasonably believes that no one competent to consent can be consulted and that a reasonable person, wishing to safeguard the welfare of the patient, would consent.

    (d) The use of physical force by an actor upon another person is justifiable when the actor acts under the reasonable belief that:

    (1)    Such other person is about to commit suicide or to inflict serious physical injury upon himself; and

    (2)    The force used is necessary to thwart such result.

    (e) The defendant shall have the burden of injecting the issue of justification under this section.

(Code 1964, § 7.680)

     State law reference(s)--Similar provisions, RSMo. § 563.061.