The case of Robson as former trustee of the estate of Samsakopoulos v Body Corporate for Sanderling at Kings Beach CTS 2942  FCAFC 143 at paragraphs 58 to 75 enters into a discussion of delegated federal judicial power that is now of increased importance for family law practitioners.
Windeyer J in Kotsis v Kotsis  122 CLR 69 at  made clear that judicial power is entrusted to courts, not individual judges.
“…. judicial power can be delegated, but only in a manner that is consistent with its character as a power entrusted to a court.”
We are reminded “all federal courts are statutory courts and are subject to constitutional limits”.
Harris v Caladine reminds us that in the case of delegated judicial power, for the delegation of judicial power “to be consistent with the constitutional character of Federal Courts, the review provided for must be a de novo review by a judge”.
The 2021 case of Bechara v Bates  FCAFC 34 said as follows:
“It is now an accepted incident of judicial power that it may be exercised in this way, namely by an order being made pursuant to a delegation, but only if the order may be reversed or otherwise corrected by a judge on review. In such cases, however, it is important to recognise that the review (or by de novo “appeal”) is not concerned with correcting error and in that respect is to be differentiated from the statutory rights of appeal that have gradually become an established part of the judicial system. Nor is it a review de novo as a further stage in a tiered process. Rather, the review is an attribute of a recognised mechanism by which the exercise of judicial power may be delegated to an officer of the Court who is not a judge, such as a registrar. The right to seek review attaches to the delegation and is an attribute of the nature of the delegated authority.”
“…the registrar’s order speaks as an order of the Court but only on the basis that it is subject to the prospect of subsequent review de novo by a judge.”
“On review, the Court hears the case again unaffected by what has gone before.”
What the case is wanting to make clear is that a review is not an appellate function.
At paragraph 64, “The ability to delegate the exercise of judicial power in the manner described is consistent with the nature of judicial power. Therefore, it is consistent with the constitutional character of a federal court for such delegation to be authorised by statute.”
An order made by a Registrar does not lose its past validity if a Judge on review decides on the review the order should not be made on the application.
An earlier order would be overtaken on review. The authority to delegate may be withdrawn. When a Registrar exercises administrative power, different considerations apply.
At paragraph 74, “….the delegation of judicial power is an important way in which to promote efficiency”.
At paragraph 75, “….in all cases, the parties (particularly the applicant) and the delegate must be conscious of the character of the delegation. If for some reason known to the applicant or the delegate it is not appropriate for the application to be determined by the exercise of delegated judicial power then that is a matter that should result in the application being referred to a judge for determination (without any prior exercise of delegated judicial power)”.