https://www.theregister.co.uk/2019/05/15/supreme_court_ipt_judicial_reviews_green_light/

Britain's Supreme Court said today that rulings from a secretive UK spy tribunal can now be appealed against after a legal challenge from pressure group Privacy International.

Decisions of the Investigatory Powers Tribunal (IPT), which rules on legal cases involving surveillance powers and the British spy agencies (MI5, MI6 and GCHQ), were previously immune from being appealed against. If you didn't like the IPT's verdict, tough – there was no way of asking a more senior judge to take a second look at it.