Commentary on sections of the Act Section 2: Definition of "electronic trade document" Exclusive control
Section 2(2)(c) requires that it must not be possible for more than one person to exercise control of the document at any one time. Section 2(3)(a), discussed below, provides that a person exercises control of a document for the purposes of the Act when they use, transfer or otherwise dispose of it.
	Requiring that it must not be possible for more than one person to exercise control of the document at any one time is not the same as precluding multiple people from having control at the same time. Multiple people could have control of a document in electronic form (because, for example, they all have the security credentials or private key necessary to use, transfer or dispose of the document). However, what is important for the document in question to qualify as an electronic trade document is that, even if multiple people have the private key or other means of control, only one person can utilise that key or means of control at any one time. The question of who actually has control is therefore separate and distinct from the question of the features that a document in electronic form must have in order to qualify as an electronic trade document for the purposes of the Act. The exclusive control requirement contained in section 2(2)(c) is aimed at addressing the double spend issue so that, for example, two people with the relevant private key cannot both transfer the same document to two different transferees independently of each other.
	A system is not excluded from the scope of the Act simply because the system operator or administrator, as well as the user, is able to exercise control of the document in electronic form. Since section 2(2)(c) focuses on exercising control, rather than having control, this removes any concern that such a system would be excluded. Systems where the system operator or administrator is able to exercise control of the document fall within the scope of the Act (assuming they meet the other criteria). The requirement that it must not be possible for more than one person to exercise control of the document at any one time ensures that where, for example, the user is transferring or otherwise using the document (thereby exercising control), the system administrator cannot also do so.