I'm not sure what the "High Passage 1" article that this references described. Does anyone have a copy that could be summarised for me to add?
The article is a bit terse, but "Justice Special Branch" or JSB, is slightly shortened from the full name, which is Ministry of Justice, Special Branch. The article is a bit at odds with later written history, but the JSB could be interpreted in much the same way MI6 or other elite intelligence organizations that were not openly acknowledged as existing for years have been. The implication is that they started by drawing extensively from Naval Intelligence but subsequently recruited from all walks.
The larger Ministry doesn't get much definition in the article, but it is implied that the Ministry of Justice is both a coordination body for multi-system law enforcement efforts, and an investigative and low level enforcement body for Imperial crimes. The Special Branch is its covert arm, was formed after the Civil War, and was not a publicly acknowledged entity until early in Strephon's reign, when he chose to make the Branch's existence public.
The article includes Prior Career tables, but the whole concept is hampered by the Classic Traveller approach of ONE AND ONLY ONE prior career. The career tables are also radically unbalanced for Classic, producing super spies routinely.
High Passage #1 was essentially a fanzine, going by the credits page. The High Passage Group teamed with FASA for later issues, and the production values show that.