Asymmetric entry-exit

Asymmetric entry-exit is a term of convenience for any set of membership requirements which is only applied (or applied more strictly) once a member has joined. (It could also be the opposite, i.e. strict rules for membership which are only applied to new members and relaxed afterwards, but this is generally less prone to abuse; the former is more like "bait-and-switch", while the latter is more like having an overly harsh warning label.)

This is analogous to the technique used in nature by the insectivorous pitcher plant: insects are lured inside the plant by enticing odors or visual cues, but once inside they encounter sticky fluids and inward-pointing barbs.

Fictional Example

 * In Babylon 5, the "Night Watch" story-arc illustrates this and several other Concepts