Which of the following is not an exception to the principles of natural justice?

The rule against direction is not one of the recognised exceptions to the principles of natural justice. Impracticability, legislative action and statutory necessity are accepted situations in which the ordinary requirements of a fair hearing or of freedom from bias may be excluded or modified: a legislative act does not call for a hearing, a statute may exclude the rules expressly or by necessary implication, and a hearing may be dispensed with where giving it is impracticable.