Voluntary Cessation

Basic Idea: when a ∆ ceases the practice that the π is suing about, the case isn't moot.

Policy Consideration: This is because you don't want ∆s to stop their behaviors for the one person who will sue, but won't stop for those who won't/everyone else.
This exception is aimed at ∆s who try to game the system once the lawsuit is filed.
Exception: a case is still moot even after voluntary cessation if there is no reasonable chance that the ∆ will resume the allegedly offending activity.
Ex: In Friends of the Earth, the issue was ruled not to be moot because—even though ∆ stopped pouring mercury-laiden waste into the environment—it did so voluntarily.
- ∆ didn't convince the Court that the challenged conduct wouldn't ever reasonably reoccur.