Montana constitution
Article II: declaration of rights
Section 30

Treason against the state shall consist only in levying war against it, or in adhering to its enemies, giving them aid and comfort; no person shall be convicted of treason except on the testimony of two witnesses to the same overt act, or on his confession in open court; no person shall be attainted of treason or felony by the legislature; no conviction shall cause the loss of property to the relatives or heirs of the convicted. The estates of suicides shall descend or vest as in cases of natural death.