The right of the state to maintain an organized militia is, however, expressly recognized by the federal constitution (Amend. II). The militia of the state consists of those persons who under the law are liable to perform military duty; and such persons may be enrolled under officers so as to be ready for service when called upon. The militia may be employed by the state in maintaining internal tranquillity and in enforcing obedience to state law, but cannot under state authority be sent outside the limits of the state unless, as suggested in the preceding paragraph, to prevent an imminent invasion. In the various states there are statutory provisions as to the organization and discipline of the militia; and so long as the state does not attempt to make use of this power for purposes forbidden by the constitution, the matter is left to state control,