Congress has delegated power to the Attorney General to execute the nation’s immigration laws, adjudicate individual noncitizens’ cases, and fill interpretive gaps in the statute. The Attorney General has in turn delegated this authority, by regulation, to the Board of Immigration Appeals (BIA). Most BIA decisions are administratively final, and noncitizens appeal unfavorable decisions directly to federal courts of appeals. In a small but growing number of cases, however, the Attorney General will step in to decide a case himself de novo after the BIA has ruled. This power of intervention and decision, sometimes known as the “referral and review” power or “certification” power, has drawn some praise for being an efficient use of the broad power afforded to the executive branch in the immigration context, but more often has sustained criticism for potential abuse. In this Note, I analyze this certification power through the lens of Chevron. In particular, I argue that Chevron deference to the BIA is appropriate because it serves the values of the Chevron doctrine—expertise, procedural regularity, and public accountability— but that Chevron deference to the Attorney General’s certified opinions is inappropriate. Courts have a responsibility under Step Zero not to defer to an interpretation of law unless its issuance adheres sufficiently to fundamental tenets of administrative law. Certified opinions are insufficient on all counts: Deference to the Attorney General’s interpretations of law issued in this manner serves none of the values of the Chevron doctrine.