Life Cycle Assessment (LCA) is a quantitative tool that measures the bundled impact of an individual product over its entire life cycle, from "cradle-to-grave." LCA has been developed over many decades to improve industry's environmental performance, and also to create environmental labels for consumer products. But in recent years, LCA has been used to inform policy and set regulatory standards. This thesis examines early experience with the first U.S. life-cycle policy: state Low-Carbon Fuel Standards (LCFS). California is the first state to implement an LCFS, which caps the total carbon intensity of the transportation fuels sold in the state. Regulators measure the carbon value of different fuels on a fuel-cycle basis, including upstream extraction, processing, harvesting, conversion, and transport. California's recent experience indicates that, while a life-cycle approach to policy brings numerous environmental benefits, LCA is not well matched to applications that rank different products or assign numeric benchmarks for dissimilar products. Further, since LCA was developed for individual products, it lacks capacity to deal with dynamic interactions, industry-wide impacts, and forecasting, all of which are important for policy decisions. As an alternative, future policies that are organized around life-cycle impacts should first establish concrete goals with a thorough planning and visioning process, and then apply LCA as an exploratory tool to determine the low-impact methods to achieve these articulated goals.