I suspect that administrative law is in the "right to contract" or "obligations of contract" realm. However, Philip Hamburger is making a good point in that it might actually be unlawful for Congress to make certain delegations in that to delegate judicial power to agencies might not even be lawful or constitutional. Also Congress cannot delegate more power than it has.
P.S. Lurking between the lines or on the sidelines or ..something ... somewhere... might be yet another term "operational law".