This case asks the Court to determine whether fuel producers, like Diamond Alternative Energy, have standing to sue the EPA for its decision to allow California to impose stricter emissions standards than those in the federal Clean Air Act. Diamond argues that, while the decision affects only car manufacturers directly, and fuel producers only indirectly, the decision’s negative consequences for conventional fuel producers are so predictable that they should be able to sue to block the decision. Petitioners further argue that not allowing those who are indirectly regulated to sue would leave them dependent on third parties who may not share their interests and give the government an incentive to impose burdensome regulations. The Environmental Protection Agency, on the other hand, contends that allowing this type of standing would undermine the purpose of the Court’s standing requirements, which is to ensure that the Court resolves real, not hypothetical disputes and that a favorable court decision for a plaintiff remedies the harm they allege. This case touches on important questions about how regulations affect a variety of parties and who can bring suit when they believe the government has harmed them.