You've got it backwards mate, a lack of enforcement isn't an agreement or resolution or much of anything reliable or solid or sound. This vacuum of enforcement actually ENABLES selective enforcement because a lack of enforcement isn't an official stance but technically at odds with the written law: It's an implicit status quo that could be changed any time and when it does, you could become retroactively liable for behavior that was acceptable under the prior status quo. That is precisely the conditions of selective enforcement: the choice of the enforcer. Under these inconsistent regulatory modalities you may insidiously lose valuable rights like: No Bill of Attainder or ex post facto Law shall be passed.