<Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (May 2008) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (May 2008) (Learn how and when to remove this template message) </Td> </Tr> <P> The four unities is a concept in the common law of real property describing conditions that must exist in order for certain kinds of property interests to be created . Specifically, these four unities must be met in order for two or more people to own property as joint tenants with right of survivorship, or for a married couple to own property as tenants by the entirety . Some jurisdictions may require additional unities . </P> <Dl> <Dt> Unity of time </Dt> <Dd> Interest must be acquired by both tenants at the same time . <Dl> <Dd> In common law, the "time" requirement could be satisfied only by using a "straw man" to create a joint tenancy . The party creating the joint tenancy would have to convey title to a straw man, who would then transfer title to the two parties as joint tenants . </Dd> </Dl> </Dd> </Dl>

One requirement of a joint tenancy is that the co-owners must be married