Certainty of Objects in McPhail v. Doulton and the Shift to the ‘Is or Is Not’ Test

Introduction

The question of whether the House of Lords correctly decided McPhail v. Doulton (No. 1) (1971) AC 424 is a contentious topic that has fueled considerable discussion in the realm of trust law. This groundbreaking case marked a turning point in the law governing discretionary trusts, particularly concerning the requirement for certainty of objects. The judgment paved the way for a more flexible test, replacing the “list certainty” test with the ‘is or is not’ test. This answer will delve into the implications of this shift.

The “List Certainty” Test and Historical Precedents

Before the McPhail v. Doulton case, the “list certainty” test was the legal principle guiding the determination of beneficiaries in discretionary trusts. This test, as established in Re Gestetner’s Settlement (1953) Ch 672 and reaffirmed in IRC v. Broadway Cottages Trust (1955) Ch 20, necessitated that trustees be able to enumerate every potential beneficiary for a discretionary trust to be valid. This strict requirement often caused the failure of trusts due to minor doubts, the practical impossibility of listing every potential beneficiary, or even minor mistakes. While ensuring certainty, this rigid approach was increasingly viewed as impractical and out of touch with the realities of trust creation and administration.

Precedent

In McPhail v. Doulton, Lord Wilberforce marked a significant departure from this established precedent. He rejected the “list certainty” test and introduced the ‘is or is not’ test. This innovative approach focused on conceptual rather than evidential certainty, demanding only the ability to determine whether an individual is or is not a member of the class of beneficiaries. This paradigm shift has triggered extensive legal discourse and remains a contentious topic.

The consequences of the “is or is not” test extend much further than they first appear. It has altered how clearly the beneficiaries of discretionary trusts must be identified, influenced the way wills and trust documents are written, and shaped the degree of freedom trustees have when carrying out their duties. Lawyers and trustees must now navigate a broader beneficiary landscape and exercise greater diligence in clarifying the terms and parameters of the trust to prevent disputes.

Support

Several compelling arguments can be made in support of the McPhail decision. Firstly, the new test is more suited to the practical realities of modern discretionary trusts, which often involve large, fluctuating, or indefinite classes of beneficiaries. The “list certainty” test was often viewed as rigid and impractical, frequently leading to the failure of trusts due to minor uncertainties. The ‘is or is not’ test provides a more flexible approach, reducing the likelihood of trusts failing due to the inability to list every potential beneficiary.

Secondly, the ‘is or is not’ test aligns with the discretionary nature of these trusts. Trustees are given the power to choose who among the beneficiaries will benefit, and it seems more logical and appropriate to identify the class conceptually rather than compile an exhaustive list of beneficiaries.

Criticism

Despite these advantages, the McPhail decision has its critics. Some argue that the new test blurs the distinction between trusts and powers, as it applies the same test to both, despite the inherently different nature of these two legal concepts. Trusts, instead of powers, involve fiduciary duties towards identifiable beneficiaries, requiring a higher degree of certainty. Moreover, the ‘is or is not’ test could potentially create uncertainty about who has the standing to enforce the trust. The “list certainty” test provided a clear list of individuals who could enforce the trust, a clarity that may be lacking under the new test.

Additionally, critics argue that the decision could lead to arbitrary behavior by trustees. The vagueness surrounding the class of beneficiaries under the ‘is or is not’ test might give trustees too much discretion, leading to potential capriciousness in their duties. A further criticism of the decision is that it may inadvertently undermine the rule against perpetuities. This principle, designed to prevent the indefinite tying up of property, requires that a trust vest within a specific period. Given that the ‘is or is not’ test permits broader, potentially indefinite classes of beneficiaries, the decision indirectly weakens this rule.

Conclusion

Determining the correctness of the McPhail v. Doulton decision requires weighing the advantages of greater flexibility against the inherent hazards of uncertainty and arbitrary application. Undeniably, the ‘is or is not’ test offers a more practical alignment with modern discretionary trusts, facilitating a more adaptable legal approach. Nevertheless, we must also recognize that this newer test risks blurring the clear lines between trusts and powers, generating potential enforcement uncertainties, and possibly undermining other well-established legal doctrines.

Ultimately, the correctness of the decision largely depends on one’s perspective and the weight one places on certainty versus flexibility. From a practical angle, McPhail represents a forward-looking shift that aligns trust law with contemporary realities. Yet, viewed strictly through a legal lens, it departs from long-standing doctrine and introduces a degree of uncertainty.

Regardless of the perspective one takes, the influence of McPhail v. Doulton is unmistakable. The decision has reshaped how trusts are formed and managed, and its effects are still felt throughout the legal landscape. It remains a key authority in trust law, and its impact will continue to guide the development of this field well into the future.

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StudyCorgi. "Certainty of Objects in McPhail v. Doulton and the Shift to the ‘Is or Is Not’ Test." March 3, 2026. https://studycorgi.com/certainty-of-objects-in-mcphail-v-doulton-and-the-shift-to-the-is-or-is-not-test/.

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StudyCorgi. 2026. "Certainty of Objects in McPhail v. Doulton and the Shift to the ‘Is or Is Not’ Test." March 3, 2026. https://studycorgi.com/certainty-of-objects-in-mcphail-v-doulton-and-the-shift-to-the-is-or-is-not-test/.

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