When it is impracticable to obtain permission, use of copyrighted material should be avoided unless the doctrine of fair use would clearly apply to the situation.
The Davis-Hammond plan's abandonment of any global capability, however, makes effective defense of our allies impracticable and invites nations that desire missile defense to proceed on their own, individually or collectively.
In federal courts, such certification must generally follow well-established principles to ensure a lawsuit would not become so large as to be impracticable, and would allow the parties to fairly represent the common interests of the larger class of plaintiffs.