Should a business rule violation throw an exception?

Question

Should a business rule violation throw an exception?

Answer 1

I would say not normally but I don't think you can say never.

For instance it depends on who/what is handling of the failed rule. If it is a user interface/user then I would use conditional logic to deal with the failure appropriately. However if it is a business rule failure in, for instance, a faceless process that logs any errors to an event log which will be monitored by for a technical resource then an exception may be just as appropriate. In this later case an appropriately named exception can be just as helpful as a nicely formatted message.