“Quis custodiet ipsos custodes?” is literally translated as “Who will guard the guard themselves?”. The phrase is generally used to denote the problem and difficulty in adequately monitoring and controlling the actions of those in power.
In recent years perhaps the most prominent example of this problem is the massive and extensive NSA surveillance and data collection program. If the NSA is watching you, who is watching the NSA? Even following reforms to NSA policy concerns remained. Following investigations into the NSA programs the evidence seemed to suggest that the NSA wasn’t really being watched.
On Tuesday it was revealed that top-secret computer code used by the NSA to break into the networks of foreign governments and other foreign espionage targets had been stolen by a group called the “Shadow Brokers”. The code effectively details how to break into foreign systems, at least as of 2013.
So the NSA is watched by hackers. Who are watched by the NSA. Who watch foreign governments. Who employ hackers to watch the United States. Ipso facto, by the transitive property the NSA is watching the United States. And we’re back to where we started.