Q. B claims that A stopped off a conduit that used to drain off the water from the roofs through A's own property. A denies that such a conduit ever existed, and points out that B himself built a ledge intercepting the alleged route of such conduit. A. Since B himself built a ledge blocking off the alleged conduit, he has no cause for action against A, and the latter need take no oath. A person who completely walls up his door leading into an alley and even removes the door posts may no longer reopen such entrance without the consent of the other dwellers in the alley. SOURCES: Cr. 240; Am II, 185; Mord. B. B. 504.