One of the pivotal principles of administrative law: that a delegate cannot delegate.
A person to whom an authority or decision-making power has been delegated to from a higher source, cannot, in turn, delegate again to another, unless the original delegation explicitly authorized it.
For example, an attorney given legal authority in a power of attorney cannot, of their own volition, delegate the exercise of that authority without the consent of the person who granted the power of attorney.
The civil law jurisdiction of Quebec, which has taken to referring to a power of attorney by the term mandate, the Civil Code 2010, at §2140 reiterates delegatus non potest delegare:
"The mandatary is bound to fulfill the mandate in person unless he is authorized by the mandator to appoint another person to perform all or part of it in his place."
The maxim is used in constitutional law as described in Mudarri v State by Justice Hunt of the Court of Appeals of Washington (footnote 2):
"The delegation doctrine prohibits delegation of legislative authority to a non-legislative branch of government. The Legislature is prohibited from delegating its purely legislative functions."
In the context of municipal law, note these words adopted by Justice Locke of Canada's Supreme Court in Vic Restaurant v Montreal:
"The exercise of a discretionary power vested in a (municipal) council cannot, in the absence of statutory authority, be delegated. A council may, however, delegate to an officer or functionary merely ministerial matters....
"Discretion confided to council ... cannot be delegated to others, as for example, requiring an applicant for a licence to get the consent of certain persons."
Further, in Vic Restaurant, Justice Cartwright deferred to these words:
"The fundamental rules that a municipal legislative body cannot delegate legislative power to any administrative branch or official, or to anyone, that it cannot vest arbitrary or unrestrained power or discretion in any board, official or person, or in itself, and that all ordinances must set a standard or prescribe a rule to govern in all cases coming within the operation of the ordinance and not leave its application or enforcement to ungoverned discretion, caprice or whim are fully applicable to the administration and enforcement of ordinances requiring licenses or permits and imposing license or permit fees or taxes.
"Administrative, fact-finding, discretionary and ministerial functions, powers and duties as to licenses, permits, fees or taxes in connection therewith can be and usually are delegated by ordinances to boards and officials. But as stated in the preceding section, any discretion vested in them must be made subject to a standard, terms and conditions established by the licensing ordinance, which must govern the board or official in granting or denying the license or the permit."