Bus iness validation - where and why?

[Ranadhir Nag]

I believe that we prefer to validate all business scenarios in teh action class;rather than the ActionForm - simply because ActionForm are meant to be contain application state that are driven by the business conditions.
So,validating business in the form is risky as the same form may be used in different scenarios needing different state and validations.

But is there any other technical reason(vis-a-via a design decision) on why the action class should be preferred over the actionForm for handling business scenarios?