ILOG's ILOG JRules 5.0, the most recent release of the enterprise Business Rule Management Systems gets excellent marks overall, especially for management, performance, document, and setup. The new release demonstrates substantial enhancement for performance when running standard benchmarks. The most compelling feature for enterprises might be JRules 5.0's support for development by users of their own rule language. This ability creates a path to faster and less mistake-prone changes to applications. JRules 5.0 continues to have good runtime performance and in-depth and detailed rule-management features. A repository for rule set management is provided, and JRules 5.0 has a shared language called Business Action Language (BAL) for collaboration on rules. The user interface permits busy analysts to create rules through combination of pre-built phrases and logical operators. Programmers have access to the foundational Java and are provided with useful debug features. JRules 5.0 increases the power and flexibility of BAL and adds performance monitoring abilities. JRules 5.1, which should be available in Summer 2005, will permit the user to construct and deploy identical rules to JRules execution server and ILOG's rule engine for Microsoft .NET. Creating a custom language is complex and time-consuming, but can give a large company the choice of making the best use of programming and business expertise.