Final answer:
Federal laws ensure consistent standards for environmental issues and help prevent a race to the bottom in regulatory standards among states. They also support programs with positive externalities, offering broader benefits across state lines.
Step-by-step explanation:
Federal laws might be a better method than state compacts to deal with widespread environmental issues like air or water pollution primarily because federal laws ensure consistent standards across states. This uniformity is crucial to prevent the problem of collective action, where states might compete in a race to the bottom, lowering standards to attract business at the expense of the environment. In contrast, state compacts may lack the enforcement power and can create additional bureaucracy, which can complicate the implementation of effective regulations. Moreover, federal laws help to maintain programs that produce positive externalities, which individual states might underfund without the assurance of federal support. This is critical in environmental issues, where the benefits of one state's regulations can extend beyond its borders, benefiting neighboring states.