i6o HARVARD LAW REVIEW. of Missouri, The plaintiff owned real estate on the Illinois side of the Mississippi River. He alleged that the city had unlawfully erected, on the Missouri side of the river, a dyke, which had caused forty acres of the plaintiff's Illinois land to be washed away. De- fendant demurred ; and, upon the argument of the demurrer, con- tended that the dyke was built under the authority of a Missouri statute, and consequently was not unlawful. The court held that the question of the lawfulness of the dyke could not be thus raised by the demurrer, and that the defendant must put in an answer setting forth its claims. But, in deciding this point. Treat, J. said, p. 440 : " Missouri cannot pass a law to govern Illinois, its citizens, and their realty situate in Illinois. If, pursuant to a Mis- souri statute, a dyke was erected destructive of property in Illinois belonging to the citizens of the latter State, such statute cannot be pleaded against them, for the Missouri statute could not operate extra-territorially. " The opinion of Attorney-General Franklin of Pennsylvania, given in 1855, and published in 4 Am. Law Register, 385-389, maintains the same view that we have taken of this question. And this view is also supported by the dicta of Story, J. 3 Mason^ p. 517, and Woodruff, J. 39 New York, p. 179. George B French. Jeremiah Smith.