The endowment effect predicts that people value losses more than gains. I examine whether the effect sheds light on courts’ takings decisions. My findings include the following: (1) regulations that emphasize losses rather than gains are more likely to survive judicial review; (2) endowments can include comprehensive plans, development plans, permits, etc; (3) both governments and landowners can acquire endowments to sway courts in their favor; (4) occupying land creates a strong endowment; and (5) implementing plans helps to cement endowments. I suggest research that examines more cases, hypotheses that emerge from my analyses, and characteristics of the effect related to land.