Facts: On August 21 2014, the four appellants were each detained in the Behavioral Management Unit (BMU) at the Don Dale Youth Detention Centre, where appellants JB and EA shared one cell and the other two appellants KW and LS shared a separate cell. JR who was not a party to the proceeding was held in a third cell. A situation arose in which JB, EA and JR caused damage to their respective cells. JR additionally opened and exited his cell, going to the exercise yard where he continued to cause damage and disturbance. The Director of Corrective Services contacted the Acting General Manager of the nearby Berrimah Correctional Facility, an adult prison, and asked him to send members of the Immediate Action Team (IAT), made up of prison officers to the detention centre. The IAT team was unable to carry out the task of recovering the debris damage or talk to JR. It was also discovered that the door between the BMU and the exercise yard, where JR was, was damaged and could not be opened. This is considered an emergency situation under the Youth Justice Act 2005 (NT) (Youth Justice Act) and on the Superintendent of the detention centre's recommendation, the Director of Corrective Services authorised the deployment of CS gas. A member of the IAT warned JR that if he did not cease his behaviour the CS gas would be deployed. JR however, did not comply and the CS gas was deployed numerous times by an officer of the team. Once JR had become compliant, the cells in the BMU were unlocked and the other detainees were removed and exposed to the CS gas which remained in the area. Litigation History: In LO v Northern Territory (2017) 317 FLR 324, the appellants initiated proceedings in the Supreme Court of the Northern Territory for assault and battery. Kelly J dismissed the claim that the use of the CS gas amounted to battery, however determined that later incidents in relation to the use of leg shackles, handcuffs and spit hoods amounted to assault [11]. Kelly J reasoned that the officers having been called upon to assist in an emergency situation at Don Dale under s 157(2) of the Youth Justice Act meant that the exemption under s 12(2) of the Weapons Control Act 2001 (NT) (Weapons Control Act) applied and that they had...all powers necessary or convenient to ensuring the safe custody of detainees under the act [124]-[125]. Then, in JB v Northern Territory (2019) 170 NTR 11, the Northern Territory Court of Appeal agreed with the reasoning of the primary judge that the officers were acting within the scope of their powers under the Youth Justice Act [118], [133]-[135]. Details of Judgment Kiefel CJ and Keane J: CS gas is dispensed using a CS fogger, which is considered a prohibited weapon under s 3 of the Weapons Control Act unless an exemption under s 12 exists, which includes use by an officer. Such an officer is defined in s 5 of the Prisons (Correctional Services) Act 2013 (NT) (Prisons Act) to mean a prison officer. Kiefel CJ and Keane J stated the question was whether the prison officer was acting as a prison officer when he deployed the CS fogger or whether he was acting in some other capacity [16]. Their Honours noted that s 62 of the Prisons Act authorised functions and actions of prisoner officers and that the use of a prohibited weapon was allowed, only as necessary to maintain the security and good order of a prisoner, or a prison, and only in a prison or police prison [17]-[18]. Their Honours declared that a prison officer's power to use a weapon was limited to a prison and did not include using a weapon in a youth detention centre [18]. Gageler J: Gageler J declared that s 9 of the Prisons Act gives all prison officers the powers and privileges of police officers, which includes the common law power to prevent a commission of a crime [28]. Gageler J stated that those powers were not displaced by the Superintendent delegating his powers to them under the Youth Justice Act [29]. His Honor held that the deployment of the gas was exempt from criminal liability under the Weapons Control Act because it was within the scope of a police officer's powers, which the IAT team member held under the Prisons Act as a prison officer who was assisting in an emergency situation [32]. His Honor, however, noted that a bystander who suffers harm through interference by the necessitous use of force of a police officer is entitled to damages compensated by the Crown [45-48]. Gageler J relied on the authority of Burmah Oil Co Ltd v Lord Advocate [1965] AC 75 to declare that compensation should be allowed if the bystander is not contributing to the possibly harmful situation that requires the police officer to use force and are themselves not at risk of greater harm if the police officer does not use force [46]. Gageler J allowed the appeals and agreed with the orders made by Gordon and Edelman JJ. Gordon and Edelmann JJ: Gordon and Edelman JJ declared that the use of the CS fogger was unlawful and not authorised by legislation [53]. They stated that s 172 of the Youth Justice Act allows the powers of the Superintendent to be delegated to the officers but does not allow them to be enlarged [83]. The Superintendent's powers in maintaining discipline at the centre does not extend to authorising the use of CS gas against detainees [101]. Further they noted that the wording in s 62 of the Prisons Act that authorises the use of weapons is specific to prisons and prisoners and does not include use in detention centres and on detainees [96]. Gordon and Edelman JJ also stated that there was no evidence of action on behalf of the appellants that authorised the officers employing their common law power to prevent an offence from occurring [105]. Their Honours concluded that the lack of authority to deploy the CS gas meant the conduct amounted to battery [109]. | 
