American livestock law turns on a date. Right-to-farm statutes took a factor the common law weighed among many — that the complaining neighbor arrived after the operation was already there — and converted it into a near-absolute statutory defense keyed to priority in time. The result is that the legal protection surrounding a livestock operation depends less on how well it is run than on when it started relative to the person objecting, and it is forfeited by the ordinary act of growing. This article explains what the common law actually did with coming to the nuisance, what the statutes replaced it with, and why expansion is the single most dangerous thing a protected operation can do. It then works through the environmental layer that right-to-farm does not touch, including why the largest operations frequently hold no federal permit at all and why the nutrient management plan decides whether runoff is exempt or unlawful. It closes with the market and slaughter rules, the two Supreme Court decisions that look contradictory and are not, and what all of this means for the people who live next door.