Related Rule
United States of America
Practice Relating to Rule 100. Fair Trial Guarantees
Section K. Public proceedings
The US Manual for Military Commissions (2007) states:
Public trial
(a) In general. Except as otherwise provided in the M.C.A. [Military Commissions Act of 2006] and this Manual, military commissions shall be publicly held. For purposes of this rule, “public” includes representatives of the press, representatives of national and international organizations, as determined by the Office of the Secretary of Defense, and certain members of both the military and civilian communities. Access to military commissions may be constrained by location, the size of the facility, physical security requirements, and national security concerns. 
United States, Manual for Military Commissions, published in implementation of the Military Commissions Act of 2006, 10 U.S.C. §§ 948a, et seq., 18 January 2007, Part II, Rule 806(a), p. II-68.
The US Manual for Military Commissions (2010) states:
Public trial
(a) In general. Except as otherwise provided in chapter 47A of title 10, United States Code, and this Manual, military commissions shall be publicly held. For purposes of this rule, “public” includes representatives of the press, representatives of national and international organizations, as determined by the Office of the Secretary of Defense, and certain members of both the military and civilian communities. Access to military commissions may be constrained by location, the size of the facility, physical security requirements, and national security concerns. 
United States, Manual for Military Commissions, published in implementation of Chapter 47A of Title 10, United States Code, as amended by the Military Commissions Act of 2009, 10 U.S.C, §§ 948a, et seq., 27 April 2010, Rule 806(a), p. II-73.
The US Regulation for Trial by Military Commissions (2007), designed to facilitate the day-to-day functioning of US Military Commissions by implementing the provisions of the Military Commissions Act of 2006 and the Manual for Military Commissions, states:
The sessions of military commissions shall be public to the maximum extent practicable. In general, all persons granted permission to attend a session except those who may be required to give evidence shall be admitted as spectators. The convening authority shall coordinate travel and attendance of spectators. Spectators must agree in writing, prior to attending any military commission trial session that if any classified or protected information is disclosed they will not publish, release, discuss or share the information identified as protected from disclosure. 
United States, Regulation for Trial by Military Commissions, 27 April 2007, § 19-7.a, p. 114.
The US Military Commissions Act (2009) amends Chapter 47A of Title 10 of the United States Code as follows:
§ 949d. Sessions
“ …
“(c) CLOSURE OF PROCEEDINGS.—(1) The military judge may close to the public all or part of the proceedings of a military commission under this chapter.
“(2) The military judge may close to the public all or a portion of the proceedings under paragraph (1) only upon making a specific finding that such closure is necessary to—
“(A) protect information the disclosure of which could reasonably be expected to cause damage to the national security, including intelligence or law enforcement sources, methods, or activities; or
“(B) ensure the physical safety of individuals. 
United States, Military Commissions Act, 2009, § 949d(c)(1) and (2).
In its judgment in the Altstötter case (The Justice Trial) in 1947, the US Military Tribunal at Nuremberg stated that “the entire proceedings from the beginning to end were secret and no public record was allowed to be made of them” and concluded, on this and other bases, that the trial of the accused was “unfair”. 
United States, Military Tribunal at Nuremberg, Altstötter case (The Justice Trial), Judgment, 4 December 1947.