4. The cases which are justified by necessity, may be classed as follows: I. For the preservation of life; as if two persons are on the same plank, and one must perish, the survivor is justified in having thrown off the other, who was thereby drowned. Bac. Max, Reg. 5.

5. - 2. Obedience by a person subject to the power of another; for example, if a wife should commit a larceny with her husband, in this case the law presumes she acted by coercion of her husband, and, being compelled, by necessity, she is justifiable. 1 Russ. Cr. 16, 20; Bac. Max. Reg. 5.

6. - 3. Those cases which arise from the act of God, or inevitable accident, or from the act of man, as public enemies. Vide dct of God; Inevitable Accident and also 15 Vin. Ab. 534 Dane s Ab h. t.; 2 Stark. Ev. 713; Marsh. Ins. b. 1, c. 6, s. 3 Jacob s Intr. to. Com. Law. Reg. 74.

7. - 4. There is another species of necessity. The actor in these cases is not compelled to do the act whether he will or not, but he has no choice left but to do the act which may be injurious to another, or to lose the total use of his property. For example, when a man s lands are surrounded by those of others, so that he cannot enjoy them without trespassing on his neighbors. The way which is thus obtained, is called a way of necessity. Gale and Whatley on Easements, 71; 11 Co. 52; Hob. 234; 1 Saund. 323, note. See 3 Rawle, R. 495; 3 M Cord, R. 131; Id. 170; 14 Mass. R. 56; 2 B. & C. 96; 2 Bing. R. 76; 8 T. R. 50; Cro. Jac. 170; 2 Roll. Ab. 60; 3 Kent, Com. 423; 3 Rawle s R. 492; 1 Taunt. R. 279; 8 Taunt. R. 24; ST. R. 50; Ham. N. P. 198; Cro. Jac. 170; 2 Bouv. Inst. n. 1637; and Way.