1.The doctrine of necessity applies both to preservation of human life and to preservation of property.
i.Preservation of property.  Ex .1  Ploof v. Putnam:  P. was sailing with his wife and children on Lake Champlain. The D’s servant unmoored their sloop and they crashed into the shore.  P was justified in mooring to the dock out of necessity.
Ex.2 Vincent v. Lake Erie The steamship Reynolds was moored to the P’s dock when storm arose. The court held that the D was liable for the damage caused by the ship banging into the dock even though they had the right to use the dock.
** Where necessity is private and involves the loss/protection of property, there is a duty to compensate the owner of the property.
ii.Preservation of human life Ex. Trolley Problem- Take one life to save five