> In cases where a regulator's action was deemed at least "reasonable", the judiciary was obligated to simply defer to the regulator's interpretation.
That is the way it _should_ be. Judges are not subject matter experts in all of human endeavors, but they are expected to make rulings over that domain. Relying on experts and career civil servants advice is generally good, unless they’re being unreasonable.
unfortunately civil servants are not perfect and not elected. If they 'take bribes' I don't want a judge to accept their word. They should have to justify their ruling before the court. The judge should defer to them only after finding their decision was good in the first place.
The role of a judge is not to give his own personal opinion on a topic. It's to listen to arguments between two different sides, who each may call upon experts, witnesses, present evidence, and so on. And they will then also argue how the other side's take is invalid or misleading. The role of the judge is to work to objectively determine which side has the law and evidence most on their side.
In cases where a judge is a domain expert, he may well end up even needing to recuse himself as that would generally entail opining on debatable topics one way or the other, which makes him unlikely to be able to effectively perform his role.