Related Rule
United States of America
Practice Relating to Rule 107. Spies
Section A. Definition of spies
The US Naval Handbook (1995) defines a spy as:
someone who, while in territory under enemy control or the zone of operations of a belligerent force, seeks to obtain information while operating under a false claim of noncombatant or friendly forces status with the intention of passing that information to an opposing belligerent. Members of the armed forces who penetrate enemy-held territory in civilian attire or enemy uniform to collect intelligence are spies. Conversely, personnel conducting reconnaissance missions behind enemy lines while properly uniformed are not spies. 
United States, The Commander’s Handbook on the Law of Naval Operations, NWP 1-14M/MCWP 5-2.1/COMDTPUB P5800.7, issued by the Department of the Navy, Office of the Chief of Naval Operations and Headquarters, US Marine Corps, and Department of Transportation, US Coast Guard, October 1995 (formerly NWP 9 (Rev. A)/FMFM 1-10, October 1989), § 12.8.
The US Manual for Military Commissions (2007), Part IV, Crimes and Elements, includes in the list of crimes triable by military commissions:
SPYING.
a. Text. “Any person subject to this chapter who with intent or reason to believe that it is to be used to the injury of the United States or to the advantage of a foreign power, collects or attempts to collect information by clandestine means or while acting under false pretenses, for the purpose of conveying such information to an enemy of the United States, or one of the co-belligerents of the enemy, shall be punished by death or such other punishment as a military commission under this chapter may direct.”
b. Elements.
(1) The accused collected or attempted to collect certain information by clandestine means or while acting under false pretenses;
(2) The accused intended or had reason to believe the information collected would be used to injure the United States or to provide an advantage to a foreign power;
(3) The accused intended to convey such information to an enemy of the United States or one of the co-belligerents of the enemy; and
(4) The conduct took place in the context of and was associated with armed conflict.
c. Maximum punishment. Death. 
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 IV, § 6(27), p. IV-20.
The US Naval Handbook (2007) states:
A spy is someone who, while in territory under enemy control or the zone of operations of a belligerent force, seeks to obtain information while operating under a false claim of noncombatant or friendly forces status with the intention of passing that information to an opposing belligerent. Members of the armed forces who penetrate enemy-held territory in civilian attire or enemy uniform to collect intelligence are spies. Conversely, personnel conducting reconnaissance missions behind enemy lines while properly uniformed are not spies. 
United States, The Commander’s Handbook on the Law of Naval Operations, NWP 1-14M/MCWP 5-12.1/COMDTPUB P5800.7, issued by the Department of the Navy, Office of the Chief of Naval Operations and Headquarters, US Marine Corps, and Department of Homeland Security, US Coast Guard, July 2007, § 12.8.
The US Manual for Military Commissions (2010), Part IV, Crimes and Elements, includes in the list of crimes triable by military commissions:
SPYING.
a. Text. “Any person subject to this chapter who, in violation of the law of war and with intent or reason to believe that it is to be used to the injury of the United States or to the advantage of a foreign power, collects or attempts to collect information by clandestine means or while acting under false pretenses, for the purpose of conveying such information to an enemy of the United States, or one of the co-belligerents of the enemy, shall be punished by death or such other punishment as a military commission under this chapter may direct.”
b. Elements.
(1) The accused collected or attempted to collect certain information by clandestine means or while acting under false pretenses;
(2) The accused intended or had reason to believe the information collected would be used to injure the United States or to provide an advantage to a foreign power;
(3) The accused intended to convey such information to an enemy of the United States or one of the co-belligerents of the enemy;
(4) The conduct was in violation of the law of war; and
(5) The conduct took place in the context of and was associated with hostilities.
c. Comment. For purposes of offenses (13) [intentionally causing serious bodily injury], (15) [murder in violation of the law of war], (16) [destruction of property in violation of the law of war], and (27) [spying] in Part IV of this Manual (corresponding to offenses enumerated in paragraphs (13), (15), (16), and (27) of § 950t of title 10, United States Code), an accused may be convicted in a military commission for these offenses if the commission finds that the accused employed a means (e.g., poison gas) or method (e.g., perfidy) prohibited by the law of war; intentionally attacked a “protected person” or “protected property” under the law of war; or engaged in conduct traditionally triable by military commission (e.g., spying; murder committed while the accused did not meet the requirements of privileged belligerency) even if such conduct does not violate the international law of war.
d. Maximum punishment. Death. 
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, § 5(27), pp. IV-21 and IV-22.
The US Military Commissions Act (2006), passed by Congress following the Supreme Court’s decision in Hamdan v. Rumsfeld in 2006, amends Title 10 of the United States Code and, inter alia, defines the term “spy” as:
Any person subject to this chapter who with intent or reason to believe that it is to be used to the injury of the United States or to the advantage of a foreign power, collects or attempts to collect information by clandestine means or while acting under false pretenses, for the purpose of conveying such information to an enemy of the United States, or one of the co-belligerents of the enemy.  
United States, Military Commissions Act, 2006, Public Law 109-366, Chapter 47A of Title 10 of the United States Code, 17 October 2006, p. 120 Stat. 2630, § 950v(b)(27).
The US Military Commissions Act (2009) amends Chapter 47A of Title 10 of the United States Code as follows:
§ 950t. Crimes triable by military commission
“The following offenses shall be triable by military commission under this chapter at any time without limitation:
“ …
“(27) SPYING.—Any person subject to this chapter who, in violation of the law of war and with intent or reason to believe that it is to be used to the injury of the United States or to the advantage of a foreign power, collects or attempts to collect information by clandestine means or while acting under false pretenses, for the purpose of conveying such information to an enemy of the United States, or one of the co-belligerents of the enemy, shall be punished by death or such other punishment as a military commission under this chapter may direct. 
United States, Military Commissions Act, 2009, § 950t(27).