The notion of “fair” trade implies that trade agreements should protect values other than pure trade liberalization. But which values must be protected in order for trade to be “fair”? This Article makes two novel contributions. First, focusing on the environmental context, it demonstrates that selective enforcement in trade law today is pervasive. Notably, instead of selectively enforcing environmental laws to gain a trade advantage—the traditional concern of critics—governments selectively enforce trade laws in ways that hurt environmental interests. Second, this Article argues that this kind of selective enforcement slows the development of competitive environmentally-friendly products. In effect, selective enforcement of trade law acts as an implicit subsidy for products with large social costs. To illustrate these two arguments, this Article evaluates how governments enforce rules that limit subsidies and other forms of government financial support for industries against programs benefitting natural resources (such as fossil fuels) and their substitutes (such as renewable energy). Lastly, this Article concludes by suggesting how governments can reform trade law enforcement to address the pernicious effects of selective enforcement.