Justification not triggered when downgrading between sublabels under same parent label

Hi all,

I am looking for confirmation of expected behaviour with Microsoft Purview sensitivity labels and justification.

We have justification enabled in our sensitivity label policy. When a user changes a label between labels that belong to the same label group, no justification prompt appears. When a user changes from a label in one label group to a label in a different label group, the justification prompt does appear as expected.

Is this behavior by design? Specifically, does Microsoft treat the label group as the enforcement boundary for downgrade justification, meaning justification is not evaluated when moving between labels within the same group, even if effective protection is reduced? If this is expected, is there any supported way to require justification when downgrading between labels in the same label group?

Thank you!