Private purpose trusts
A requirement concerning express private trusts is the need to identify beneficiaries who are capable of enforcing the trust. A trust is mandatory in nature and imposes enforceable obligations on the trustees. Those capable of enforcing such obligations are the beneficiaries. These persons are granted rights in rem in the subject-matter of the trust. If an enumeration of purposes outside the realm of charities can take the place of an enumeration of beneficiaries, the purposes must be stated in phrases which embody definite concepts and the means by which the trustees are to try to attain them must also be prescribed with a sufficient degree of certainty. The perpetuity rule is a common law principle of general application in property law which restricts the maximum period in which the vesting of property, real or personal, may be postponed.