Imagine, for example, a case is about someone disclosing the location of nuclear arms to their spouse. Maybe even accidentally. If they are brought up on charges about this, national security doesn't want the fact that a case is about nuclear weapons to be public information. They further don't want it disclosed who was told about them (as the spouse wouldn't be subject to charges). That's basically where a secret interpretation and ruling would ultimately enter. The courts can't disclose what the ruling was nor what the case was even fully about.
Imagine, for example, a case is about someone disclosing the location of nuclear arms to their spouse. Maybe even accidentally. If they are brought up on charges about this, national security doesn't want the fact that a case is about nuclear weapons to be public information. They further don't want it disclosed who was told about them (as the spouse wouldn't be subject to charges). That's basically where a secret interpretation and ruling would ultimately enter. The courts can't disclose what the ruling was nor what the case was even fully about.