This question clearly relates to an ongoing matter but I’m not given specific facts nor would it be appropriate to comment on them even if I was. This answer will therefore be quite limited to the question asked:
I am interested in a fundamental aspect related to a series of allegations made against a crew of five volunteers on interstate deployment:
Does the NSW Rural Fires Act apply to NSW RFS members [paid or volunteer] performing duties at a fire as part of a NSW RFS interstate deployment?
If it does are there any limits to its applicability? For example, do the authorities associated with the various ranks of the RFS apply interstate?
This is a complex issue and depends to a large extent on the particular circumstances and interpretation rather than a clear rule. The answer must be as follows:
The Rural Fire Service is an entity created by the Rural Fires Act 1997 (NSW) s 8. People join the RFS (s 20) and when they deploy interstate they are part of the RFS. If the provisions that govern the operation of the RFS didn’t apply interstate, then the deployment would not be by the RFS but by a group of individuals who happen to belong to the RFS. To put that another way, it is the RFS that goes interstate. Like any corporate entity the RFS is a fiction, it doesn’t physically exist. The RFS’ physical existence is created by the assets and people that are part of it. Those firefighters that go interstate are the RFS so must be governed by the RFS procedures including the rank structure and the disciplinary provisions.
What can’t apply interstate is the RFS provisions that allow the RFS to do something contrary to the rights of others. So, for example, in NSW
(1) An officer of a rural fire brigade or group of rural fire brigades may for the purpose of controlling or suppressing a fire:
(a) take and use without any payment any water from any source on any land… (Rural Fires Act 1997 (NSW) s 26)
But that authority could hardly be extended interstate particularly if it conflicted with interstate law – for example in Western Australia
… for the purpose of controlling and extinguishing or preventing the occurrence or spread or extension of a bush fire, or for any other prescribed purpose, the captain … of a bush fire brigade … may —
(d) enter or give directions for entering land or premises, and take or cause to be taken water from any source whatsoever, other than … the domestic supply of an occupier contained in a tank at his dwelling-house, …(Bush Fires Act 1954 (WA) s 44).
It would be inconsistent if a member of the NSW RFS in WA could rely on the NSW Act to enter land and take water that is ‘the domestic supply of an occupier contained in a tank at his dwelling-house’ when a WA fire brigade captain could not take that water.
How the chain of command would work would have to depend on the arrangements in place. First under AIIMS there must be an incident controller – the incident controller will be in ‘control’ of the response, the RFS team leader will be in ‘command’ of the RFS contingent. The interstate authorities (depending on the state) will have legislative power to control the movement of people in the fire ground and direct fire fighting operations. Assume the RFS is allocated a sector of the fire and they are working independently then the RFS commander would, subject to the directions of the incident controller, be responsible for the discipline of the RFS members. Another example might be that the interstate authority is working in the area and the RFS members are reporting to the sector commander from the local authority. Whilst the RFS team leader would still be ‘in command’ of RFS members, they could not give directions contrary to the sector commander or IC and certainly an RFS senior officer could not start directing the RFS in a way that is inconsistent with the Incident Action Plan and the orders of the local authority. But if the RFS members were not obeying directions or otherwise acting in ‘breach of discipline’ responsibility for them would always fall back to the RFS in it’s ‘command’ role.
The key disciplinary provision is found in the Rural Fires Regulation 2013 (NSW) r 9. That says:
(1) An officer or member of a rural fire brigade or group of rural fire brigades is guilty of a breach of discipline if the officer or member:
(a) contravenes the Act or a provision of this Regulation, or
(b) is negligent, careless, inefficient or incompetent in the discharge of his or her duties, or
(c) fails to comply with the Service Standards.
It may be that when interstate it is not possible to comply with some provision of the Act or Regulations because all though the conduct required is lawful in NSW it is not lawful in the other state. Such a situation is possible, but unlikely. To take my water example a firefighter does not ‘breach’ the RFS Act if he or she fails to take water from any source so complying with the WA provision would not represent a ‘contravention’ of the NSW Act. Nor would it be ‘negligent’ even if, in NSW, one would expect a fire fighter to take that water to fight the fire. What is negligent depends on what is ‘reasonable’ and it is ‘reasonable’ to comply with the law in the relevant jurisdiction. If, however, we assume for the sake of the argument that there is some NSW provision that says ‘a fire fighter must …’ and an interstate provision that says ‘a fire fighter must not …’ then that must be considered when deciding whether an offence under regulation 9(1)(a) is established.
On the other hand, a member of the RFS could be ‘negligent, careless, inefficient or incompetent in the discharge of his or her duties’ both in NSW and interstate and if that is the case there may be a question mark over their continued membership of the RFS. The RFS have to be able to deal with that whether the alleged incident occurred in NSW or elsewhere.
Conclusion
Exactly what provisions can be applied interstate would be a matter of interpretation and consideration of the actual circmstances, but it has to be axiomatic that the provisions governing internal discipline have to apply in order for the task force to be an RFS task force, and not just a group of individuals.
Australian Emergency Law 
I received this question by email but I post it here with my answer:
“In relation to your post on Maintaining discipline while interstate, would the interstate assistance provisions in the emergency service legislation of each state have an impact on this issue? For example, if an interstate fire brigade is in NSW assisting the Rural Fire Service, the provisions of Section 43 of the Rural Fires Act apply. My understanding is that each state has similar provisions.”
Section 43 of the RFS Act says:
(1) A person who is a member of an interstate fire brigade and is present at a fire within a rural fire district for the purpose of mitigating or suppressing that fire must:
(a) obey any orders given to the person by the officer in charge at the fire, and
(b) place any gear or equipment in the person’s charge at the disposal of the officer in charge at the fire.
(2) While there is no officer in charge at the fire, the member of the interstate fire brigade who has the charge of the members of that brigade present at the fire is, for the purposes of this Act, to be considered the officer in charge at the fire.
(3) A member of an interstate fire brigade who is present at a fire within a rural fire district for the purpose of mitigating or suppressing that fire is taken to have and may exercise all the functions that, if the fire were in the area of a rural fire brigade, the officer in charge of that rural fire brigade would have and be capable of exercising and performing.
Not every state does have an equivalent but even where there isn’t something so specific there are provisions to allow the OIC to take charge of brigades and others that make themselves available to assist and that would include visiting brigades.
This is the point I was trying to make about having to take into account particular circumstances. If we change the story so that say a brigade from Tasmania is assisting in NSW, the Tasmanian officers remain ‘in command’ of their contingent and the relevant Tasmania law on authority and discipline would be in force but it would have to be tempered by reference to NSW law. So a member of the Tasmania Fire Service in NSW is expected to follow the directions of his or her senior officers as well as the orders given by the person in charge of the NSW fire. As for the original question it was put this way ‘do the authorities associated with the various ranks of the RFS apply interstate’? In this version of events change RFS to TFS and the answer is that the authorities of the various ranks apply but subject to and therefore constrained by the authority of, in this case, the NSW officer in charge of the fire.