Re Gulbenkian’s Settlements Trusts [1968] is an English trusts law case, concerning the certainty of trusts. It held that while the 'is or is not' test was suitable for mere powers, the complete list test remained the appropriate test for discretionary trusts. It was only a year later in McPhail v Doulton that the 'is or is not' test was considered appropriate for discretionary trusts by a different panel of their lordships.