It has been nearly 40 years since the Supreme Court indicated in Chevron v. Natural Resources Defense Council that courts should defer to an agency’s reasonable interpretation of an ambiguous statute. After more than three-and-a-half hours of oral argument on Wednesday‚ it seemed unlikely that the rule outlined in that case‚ known as the Chevron doctrine‚ will survive in its current form. A majority of the justices seemed ready to jettison the doctrine or at the very least significantly limit...