15.16 Spying

It is prohibited to join a city with the intent to spy on that city or otherwise sabotage their efforts in any way. If you are joining a city, you must be joining in good faith.

There's several reasons for this, but largely the existence of this style of spying breeds distrust in cities, creates a toxic environment, and encourages people to exclude citizens in favour of a clique.

You may still engage in normal espionage methods (e.g. eavesdropping), and the rules surrounding these are permissive.