Implementing Open Policy Agent (OPA) with Harness streamlines authorization modifications across microservices by centralizing policy decisions, which enhances both security and operational efficiency. As distributed systems grow, managing authentication and authorization becomes crucial, often requiring deployments for permission changes. OPA addresses this by decoupling policy decision-making from enforcement, using JSON for data and queries, and Rego for policy logic. The article outlines a step-by-step guide to installing OPA's GateKeeper on a Kubernetes cluster using Harness, emphasizing the simplicity and effectiveness of this integration. With Harness, deploying OPA and adapting to new technologies is made easier, supporting changes at scale. The discussion highlights the partnership and visionary roles of Styra and Harness in advancing OPA methodologies.