The perm is an ambiguous delegation.

Delegators can also be explicit in the other direction: that is, to make clear that they do not divest themselves of authority. Most commonly, agency heads explicitly “reserve” authority to exercise the delegated power themselves. Sometimes they issue blanket reservations of authority. The Secretary of Transportation, for example, declares that “except as otherwise provided,” she “may exercise powers and duties delegated or assigned to officials other than the Secretary.” 95 Alternatively, subdelegations can also specify reservations for individual grants of power. The Secretary of Agriculture specifically reserves authority from a delegation to the Under Secretary for Trade and Foreign Agricultural Affairs on issues “related to foreign agriculture” and for “[a]pproving export controls.” 96 Under these circumstances, courts generally decline to apply Accardi since the rule itself retains authority in the initial delegator.97 Between these two poles are a host of delegations that are ambiguous: they lack both clear reservations of authority and explicit intent to divest authority completely. Unfortunately, our dataset does not capture which delegations fall into each of these categories given the challenges of collecting and coding data on reservations of authority. Reservations, whether blanket or individual, are often placed in different parts of the Code of Federal Regulations and have idiosyncratic appearances in the Federal Register. They must be matched, often manually, with each delegated power through cross-references. Nevertheless, to try to get some sense of magnitude, we drew a random sample of 200 of the delegations in our dataset and found only two for which explicit reservations were present in the same Federal Register entries. Further, none of the 200 delegations in this sample included an express statement of divestment within the same entry. For these more ambiguous rules, judges will defer to the agency after deploying the ordinary tools of regulatory interpretation. 98