Under WTO law, temporary trade barriers such as antidumping duties must be removed after a period of four or five years. However, under rather vague legal conditions, they can be renewed. This institutional environment provides the structure to carefully study the determinants of the \textit{length} of protection. We present a theoretical political-economy model of the renewal process and find that the probability a temporary trade barrier will be renewed decreases in the level of trade agreement tariffs and is also likely to decrease in the level of the anti-dumping duties. An increase in an industry’s profitability is shown to increase the probability of renewal also increases. Lobbying effort also increases the probability for a fixed strength of the lobby, while the strength of the lobby itself has more nuanced effects on the renewal probability.