5. Agency Head
combination of functions
Due process does not necessarily prohibit the combination of investigation and decisionmaking, each case must be resolved on its own peculiarities.  Advocacy and decisionmaking may entail a much greater risk.  Specific statutes may impose greater prohibitions on combination of functions than is required under minimal due process.
ex parte contact, adjudication
Ex parte contact may give rise to disqualifying bias, especially if it involves the agency head in a personal or financial interest in the outcome.  Given the broad range of duties of the agency head, however, it may be impossible to isolate the decisionmaker.  Stricter prohibitions may be imposed on the ALJ under an APA.
personal decision
The agency head is generally responsible by statute for making all final decisions. Decisionmaking usually requires a personal decision, but the question becomes one of how much preliminary assistance can be given to the agency head.  In the range of agency actions, the most sensitive requirements of personal decisionmaking involve adversarial adjudications while the least sensitive involve notice and comment rulemaking.  The agency head frequently must make a personal decision and not simply rubberstamp a decision made by staff.  This does not mean that the agency head must personally read all of the record or write the decision.  The usual requirement is that the agency head be aware of major issues and use some personal mental faculties in making the decision.  The requirement for a personal decision does not mean that the agency head can be called to court to testify whether or not that was the way a particular decision was made.  Outside advisory groups may be permitted to assist the decisionmaker so long as the sanctity of the record is maintained, the final decision is personal with the decisionmaker, and the decision is made on the basis of the statutory factors alone.