Mo. Rev. Stat. § 557.021: Classification of offenses outside this code.

1. Any offense defined outside this code that is declared to be a misdemeanor without specification of the penalty therefor is a class A misdemeanor.

2. Any offense defined outside this code that is declared to be a felony without specification of the penalty therefor is a class E felony and subject to the terms as provided in chapter 558.

3. For the purpose of applying the extended term provisions of section 558.016, the parole eligibility provisions pursuant to section 558.011 and for determining the penalty for attempts, offenses defined outside of this code shall be classified as follows:

(1) If the offense is a felony:

(a) It is a class A felony if the authorized penalty includes death, life imprisonment or imprisonment for a term of twenty years or more;

(b) It is a class B felony if the maximum term of imprisonment authorized exceeds ten years but is less than twenty years;

(c) It is a class C felony if the maximum term of imprisonment authorized is ten years;

(d) It is a class D felony if the maximum term of imprisonment exceeds four years but is less than ten years;

(e) It is a class E felony if the maximum term of imprisonment is four years or less;

(2) If the offense is a misdemeanor:

(a) It is a class A misdemeanor if the authorized imprisonment exceeds six months in jail;

(b) It is a class B misdemeanor if the authorized imprisonment exceeds thirty days but is not more than six months;

(c) It is a class C misdemeanor if the authorized imprisonment is thirty days or less;

(d) It is a class D misdemeanor if it includes a mental state as an element of the offense and there is no authorized imprisonment;

(e) It is an infraction if there is no authorized imprisonment.