Related Rule
Canada
Practice Relating to Rule 108. Mercenaries
Canada’s LOAC Manual (1999) states:
A mercenary is a person who:
a) is specially recruited locally or abroad in order to fight in an armed conflict;
b) does, in fact, take a direct part in the hostilities;
c) is motivated to take part in the hostilities essentially by the desire for private gain and, in fact, is promised by or on behalf of a Party to the conflict, material compensation substantially in excess of that promised or paid to combatants of similar ranks and functions in the armed forces of that Party;
d) is neither a national of a party to the conflict nor a resident of territory controlled by a Party to the conflict;
e) is not a member of the armed forces of a Party to the conflict; and
f) has not been sent by a State which is not a Party to the conflict on official duty as a member of its armed forces. 
Canada, The Law of Armed Conflict at the Operational and Tactical Level, Office of the Judge Advocate General, 1999, p. 3-4, § 30.
Canada’s LOAC Manual (2001) states in its chapter entitled “Combatant Status”:
1. A mercenary is any person who:
a. is specially recruited locally or abroad in order to fight in an armed conflict;
b. does, in fact, take a direct part in the hostilities;
c. is motivated to take part in the hostilities essentially by the desire for private gain and, in fact, is promised, by or on behalf of a party to the conflict, material compensation substantially in excess of that promised or paid to combatants of similar ranks and functions in the armed forces of that party;
d. is neither a national of a party to the conflict nor a resident of territory controlled by a party to the conflict;
e. is not a member of the armed forces of a party to the conflict; and
f. has not been sent by a state which is not a party to the conflict on official duty as a member of its armed forces. 
Canada, The Law of Armed Conflict at the Operational and Tactical Levels, Office of the Judge Advocate General, 13 August 2001, § 319.1.
Canada’s LOAC Manual (1999) states:
Mercenaries are unlawful combatants and may be attacked for such time as they take a direct part in hostilities. If captured, mercenaries are not entitled to PW [prisoner-of-war] status. They may be punished for being mercenaries but only following a fair trial affording all judicial guarantees. 
Canada, The Law of Armed Conflict at the Operational and Tactical Level, Office of the Judge Advocate General, 1999, p. 3-4, § 31.
Canada’s LOAC Manual (2001) states in its chapter entitled “Combatant Status”:
Mercenaries are unlawful combatants and may be attacked for such time as they take a direct part in hostilities. If captured, mercenaries are not entitled to PW [prisoner-of-war] status. They may be punished for being mercenaries but only following a fair trial affording all judicial guarantees. 
Canada, The Law of Armed Conflict at the Operational and Tactical Levels, Office of the Judge Advocate General, 13 August 2001, § 319.2.
In its chapter on the treatment of prisoners of war (PWs), the manual further states: “If captured and detained, the following persons are not entitled to PW status, but they must nevertheless be treated humanely: … b. mercenaries”. 
Canada, The Law of Armed Conflict at the Operational and Tactical Levels, Office of the Judge Advocate General, 13 August 2001, § 1007.1.b.
[emphasis in original]
At the CDDH, Canada stated that it “welcomed the recognition by the Nigerian representative that mercenaries were entitled to the fundamental guarantees provided in Article 65 [now Article 75 of the 1977 Additional Protocol I]”. 
Canada, Statement at the CDDH, Official Records, Vol. VI, CDDH/SR.41, 26 May 1977, p. 160, § 98.