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Proxy re-encryption is a cryptographic primitive used to transform a ciphertext under one public key such that it becomes a ciphertext under another public key using a re-encryption key. Depending on the properties featured by a proxy re-encryption scheme, it can be applied to a variety of applications. In this paper, we target one such application of proxy re-encryption–access control in hierarchy, to highlight an important research gap in its design. We study how a proxy re-encryption scheme that is both unidirectional and transitive can be useful for enforcing hierarchical access control with constant computation and storage overhead on its users irrespective of the depth of the hierarchy. Also, we present improvements on the existing re-encryption schemes to make it applicable to hierarchical key assignment and achieve performance closer to that in case of a unidirectional transitive proxy re-encryption scheme.