Notes and Questions 16.1

Co-ownership 577

for a tenancy in common. We will briefly consider this aspect of the distinction, but before doing so we should note the comments of Deane J who, in Corin v. Patton (1990) 169 CLR 540 at 572–3, cautions how the ‘traditional ritual’ of the four unities ‘cloaks some obscurity of precise meaning, some overlapping between the unities and some conceptual difficulties about the essential character of joint tenancy’. Indeed, it is hard to find any case in which the appealing symmetry of the four unities has played any significant role beyond that which arises in the context of shareholdings under unity of interest. In reality, at least when considering the unities of title and time, they are no more than descriptions of the nature of a joint tenancy rather than hallmarks of authenticity – useful as an illustration but too imprecise for much else beyond.

Unity of possession

Unity of possession is critical to co-ownership, not only to joint tenancies and tenancies in common but also to the non-traditional examples of co-ownership we will consider below insofar as possession is a component of that shared right. It expresses the idea that all co-owners have the same right to use the thing as their fellow co-owners. Thus all the joint tenants of the fee simple estate in Blackacre have an equal right to possess the whole; as do all the tenants in common of a racehorse; and all the members of an association in respect of its assets (although they might, of course, collectively agree to limit the individual members’ exercise of that right) – for how else can each individual in each group of co-owners enjoy their property rights in the shared thing?

Unity of interest

Unity of interest goes beyond unity of possession, signifying not only that all the co-owners have the same right to use the co-owned thing during the currency of their co-ownership but that the right to use arises from the same interest. In many respects, it is the one unity that, at a practical level, differentiates joint tenancies from tenancies in common. Thus under a joint tenancy of Blackacre all the co-owners own the same shared interest rather than separate shares in the same interest which is the hallmark of a tenancy in common. As Bagnall J noted in Cowcher v. Cowcher [1972] 1 WLR 425, ‘[a] joint interest in equal shares is a contradiction in terms’ because each joint tenant is joint owner of the whole rather than an individual owner of his share in the whole. True, as we know from the unity of possession requirement, the interests of the tenants in common have not been divided up (hence the use of the term ‘undivided share’ to refer to the tenant in common’s interest) but it is, nonetheless, a share in the whole, rather than a shared whole that they each own. It follows from this that the quantum of each share can (but does not have to) vary under a tenancy in common, although, as Bagnall J noted above, all talk of shares (be they equal or unequal) brings us squarely within the territory of the tenancy in common and breaks the unity of interest required under a joint tenancy.