The taxpayer and his wife allowed a charity to use two rooms of their house for free (an office and a storage room), and claimed charitable credits for the fair market value of the use of the rooms (i.e. rent). C Miller J disallowed these credits, as the charity had no legally enforceable right to the space - and without an enforceable right, there was no property to donate.
However, C Miller J disagreed with CRA's position in 2003-0018595 that a grant of use cannot constitute a transfer of property. Manrell provides that "property" entails some exclusive right to make a claim against someone else (para. 6).