Under the Chevron doctrine, courts defer to plausible interpretations of the law set forth by regulatory agencies, even when the court thinks it has a better reading of the legal text. Chevron deference was established by the Supreme Court in 1984 and has since become the most widely known holding in administrative law.

The constitutional problem with the Chevron doctrine is that, within our tripartite government, it is the courts’ emphatic duty “to say what the law is,” as Chief Justice John Marshall famously explained. Under Chevron, judges do not “say what the law is,” but instead pass off that task to executive branch agencies. In this manner, the doctrine strains the separation of powers, which is a crucial bulwark for liberty.

Apart from these constitutional concerns, there is also a practical problem with Chevron deference—namely, courts are applying two different versions of the doctrine. The Supreme Court doesn’t even mention Chevron in about 75 percent of the cases where it could apply, and, in the minority of cases where the Court considers the Chevron framework, the trend during the Roberts era has been to limit the doctrine’s scope. While the Supreme Court has been ignoring or narrowing the Chevron doctrine, circuit courts routinely apply it, deferring in almost 80 percent of the cases where it’s sought by the government, according to one study. Simply put, the Chevron doctrine carries a lot more weight in the lower courts than it does at the Supreme Court.

Due to a reflexive application of Chevron deference by a three-judge panel of the Veterans Court, Thomas Buffington lost his challenge to a Department of Veterans Affairs decision regarding the timing of disability benefits to which he was entitled after serving in the Iraq War. A divided Federal Circuit panel affirmed, again relying on Chevron deference. Now, Mr. Buffington seeks Supreme Court review.

Today, the Cato Institute, joined by the National Right To Work Legal Defense Foundation, filed a brief in support of the petitioner. We urge the Court to take this case and harmonize the disparate versions of the Chevron doctrine that are being applied by the judiciary.