The Policy Custodian role is assigned the responsibility of defining and maintaining machine-language (technical) and natural-language (human-readable) policies used by service contracts and policies assigned to services in general. Although this role can be assumed by the same person acting as a Schema Custodian, it is not uncommon for different individuals (or even different groups) to be responsible for defining and maintaining policies.

Policy Custodians are often required to ensure that operational service policies remain in alignment with parent business policies. This can further lead to unique versioning requirements as business policies can be subject to various changes that end up affecting service contracts.