Article 1, Section 8, Clause 16

Document 12

James Iredell, Proposed Amendment, North Carolina Ratifying Convention

3. Each state respectively shall have the power to provide for organizing, arming, and disciplining, its own militia, whensoever Congress shall omit or neglect to provide for the same. The militia shall not be subject to martial law, except when in actual service in time of war, invasion, or rebellion; and when they are not in the actual service of the United States, they shall be subject only to such fines, penalties, and punishments, as shall be directed or inflicted by the laws of its own state.

The Founders' Constitution
Volume 3, Article 1, Section 8, Clause 16, Document 12
http://press-pubs.uchicago.edu/founders/documents/a1_8_16s12.html
The University of Chicago Press

Elliot, Jonathan, ed. The Debates in the Several State Conventions on the Adoption of the Federal Constitution as Recommended by the General Convention at Philadelphia in 1787. . . . 5 vols. 2d ed. 1888. Reprint. New York: Burt Franklin, n.d.