... Chevron is overruled. Courts must exercise their independent judgment in deciding whether an agency has acted within its statutory authority, as the APA requires. Careful attention to the judgment of the Executive Branch may help inform that inquiry. And when a particular statute delegates authority to an agency consistent with constitutional limits, courts must respect the delegation, while ensuring that the agency acts within it. But courts need not and under the APA may not defer to an agency interpretation of the law simply because a statute is ambiguous.
Because the D. C. and First Circuits relied on Chevron in deciding whether to uphold the Rule, their judgments are vacated, and the cases are remanded for further proceedings consistent with this opinion.
It is so ordered.
