Here's the background: I'm doing research on war criminals convicted by international courts and came up with some striking statistics. Over 80 percent of international convicts have been granted early release without being put on parole. Only one international convict is currently out on parole, making him (a/an/the) __________ anomaly. Is there a word that denotes something that's anomalous in a particular context, but is common or assumed in general contexts?
If a particular event is something that would usually be expected but, appearing in the context of surrounding events which - being themselves non-standard - cause it to stand out from its background, then it is a 'normative anomaly'.
That is to say, it is something that is normative but, due to the unusual circumstances in which it occurs, it is anomalous to non-standard surrounding data.
It is time to incorporate the normative anomaly and undertake an investigation [...]
Normative Anomaly. The validity of Laws Clause caused a unique legal situation [...]
The paragraph headed 'Normative Anomaly' in the above quote from Human Dignity explains the term in context.