A  Business Rule is a rule that is under business jurisdiction.

A rule’s being under "business jurisdiction" means that it is under the jurisdiction of the community that it governs or guides - that the community can opt to change or discard the rule. Laws of physics may be relevant to an Enterprise; legislation and regulations may be imposed on it; external standards. These things are not  Business Rules from the company’s perspective, since it does not have the authority to change them.

The company will decide how to react to laws and regulations, and will create  Business Rules to ensure compliance with them. Similarly, it will create  Business Rules to ensure that standards or best practices are implemented as intended.