Ron Ross again brought up the question of “Exceptions to Business Rules”. Ron defines an exception to the rules as a foreseen, explicit set of circumstances in which different-than-normal guidance is to be followed. He gave an example: seeing-eye dogs as an (explicit) exception to dogs not being allowed in a hospital. One comment says: “I heard that there are no exceptions to the BRs. I heard that there are only other BRs.”
This discussion is still as important as it was years ago when we, vendors of Business Rules systems, considered it as a more generic problem of Resolving Conflicts among Business Rules.

In 2014, two BR vendors, Drools and OpenRules, independently addressed the problem of the diagnosis and resolution of business rule conflicts using Defeasible Logic. Mark Proctor (Drools) and I (OpenRules) proposed two completely different implementations:

• Drools forced the author of a rules-based decision model to explicitly define the superiority relationships between all the contradictory rules using so-called defeasible rules.
• OpenRules proposed more flexible defeasible rules by introducing a relative “rule probability” (or rule likelihood). Regular “strict” rules become “hard” constraints, while rules with probabilities become “soft” constraints with a possible violation cost. Then, we automatically solved the problem by minimizing the total constraint violation for all defeasible rules.

You can analyze both approaches by looking at this 2014 presentation. If you need to resolve conflicts between your business rules using a modern Decision Intelligence platform, you may utilize http://RuleSolver.com.