One of the interesting uses of business rules is in the hot topic of legacy modernization. Many organizations have large investments in mainframe applications, written in COBOL or another hard to maintain languages. When these systems are evaluated they typically turn out to be costly to maintain - each change to the system takes time and money out of all proportion to the value of the change. This leads many organizations to replatform and reimplement these systems.
However, more careful analysis such as that done by the California DMV can lead to an interesting insight - much of a typical mainframe system is static, works fine and needs no maintenance. Often only a small portion of the system is responsible for much of the maintenance work. DMV found that this was the case with their system - the portion of the system that dealt with managing vehicle information, printing bills etc hardly ever required changes. The part that dealt with license fee calculation, the business rules in other words, required changes whenever the legislature changed the law. If this one component could be re-engineered to use a business rules technology, they reasoned, almost all their legacy maintenance work could be replaced with business rules management. Thus they were able to increase their agility and reduce their costs without having to replace the whole system simply by integrating Blaze Advisor with their legacy system and replacing the hard coded rules with rules managed using Blaze Advisor.
If you want to try these rules out yourself, you can. Check out the Vehicle Registration Fee Calculator or read about the awards this system won - Intelligent Enterprise RealWare Award and Application Development Trends Innovator Award.