Widely adopted for more than 20 years in industrial fields, business rules offer the opportunity to non-IT users to define decision-making policies in a simple and intuitive way. To facilitate their use, systems known as Business Rule Management Systems have been developed , separating the business logic from the application one. While suitable for processing structured and complete data, BRMS face difficulties when those are incomplete or uncertain. This study proposes a new approach for the integration of probabilistic reasoning in IBM Operational Decision Manager (ODM), IBMs BRMS, especially through the introduction of a notion of risk, making the compilation phase more complex but increasing the expressiveness of business rules.