It's not a judicial review, the PKG (parliamentary control committee) and the G10 Kommittee, which is a subset of the PKG, both consist of members of Parliament, and they do the same work (keeping an eye on the executive branch's work) - just for efforts whose information is considered too sensitive for wider distribution.
"Die anstelle gerichtlicher Prüfung des Sachverhalts vorgesehenen politischen Kontrollgremien haben sich in der Vergangenheit aber oft als unzulänglich erwiesen:"
translates to (while keeping the sentence structure the same as much as possible, even if that sounds a bit off in english):
"The, in place of judicial review of the factual matter, arranged political control committees have shown in the past to often be insufficient:"