Business rules are system wide preferences.  They are pre-defined or user-defined preferences that control functions and displays throughout the program.  Business rules are accessed from Configuration on the navigation bar.  Business rules apply to everyone (global) unless specified that they apply to certain security groups when setting up the rule.

Business rules help speed system-wide data entry and verify its consistency.

Note: Access to Business Rules can be restricted by limiting the security group rights. In the security group highlight Configuration and click Options. Mark or unmark the Business Rules checkbox.

The Raiser's Edge 7:
Examples of how to use business rules include setting options for how to handle deceased constituents, determine how to assign batch numbers, whether to automatically assign IDs, and whether the system should warn users entering gifts if the constituent has an outstanding pledge balance.

The Financial Edge
Examples of how to use business rules include using Business Rules you can turn on the rule Journal entry batches must be approved before they can be posted, and restrict rights to who can approve batches.  You can also turn on the rule to Allow automatic creation of interfund entries in journal entry to ease the process of transferring money between funds.