Knight v Knight [1840]

Knight v Knight (1840) 49 ER 58 is a leading authority in English trust law for articulating the foundational principle of the three certainties, which must be satisfied for a valid trust to be created. The case establishes that, for equity to recognise a trust, there must be certainty of intention to create a trust, certainty of subject matter, and certainty of objects. If any of these elements is missing, no trust arises and the purported trustee will instead take the property absolutely. The decision has become a cornerstone of trust law and is regularly cited in determining whether testamentary or inter vivos dispositions create binding trusts or merely express non-binding wishes.

The dispute arose from a complex family settlement involving substantial landed estates. Payne Knight left property to his brother, Thomas Knight, with the estate passing down the male line. In his will, however, he added language stating that he “trusted to the liberality” and “justice” of his successors to reward servants and tenants and to continue the estates in the male succession. After Thomas died intestate and without a surviving son, more distant male relatives argued that this wording imposed a binding trust that required the property to be settled strictly in favour of the male line. In contrast, Thomas’s daughter and her husband contended that the words were merely expressions of hope or moral expectation and did not create legal obligations.

Lord Langdale MR held that no trust had been created. He found that the language used in the will was precatory rather than mandatory. Words such as “trust to the liberality” did not demonstrate a clear intention to impose legally enforceable duties on the recipient. Instead, they amounted only to an expression of confidence or hope. As a result, Thomas Knight took the property absolutely, free from any trust, and was not bound to settle it for the benefit of the wider family.

In reaching this conclusion, Lord Langdale articulated the now famous test for the creation of a valid trust. He explained that there must be three certainties:

• Certainty of intention: There must be a clear intention to create a trust.
• Certainty of subject matter: The assets constituting the trust must be readily determinable.
• Certainty of objects: The individuals to whom the trustees owe a duty must be readily determinable.

Because the will failed at the first stage, there was no need to consider the others in detail.

The significance of Knight v Knight lies in its clear formulation of these three requirements, which continue to guide courts in distinguishing between enforceable trusts and non-binding moral wishes. The case marked a shift away from treating vague or precatory language as creating trusts and reinforced the principle that equity will only enforce arrangements that are expressed with sufficient legal certainty. It remains one of the most frequently cited authorities in trust law and forms the starting point for any analysis of whether a trust has been validly constituted.