The distribution of casualty points on units is done automatically according to the units' value. Is this the designers' choice or is it following boardgame's rules? In the later case, what are these rules and which player decide how to apply the points?
The distribution of casualty points, as we have implemented it, is pretty reasonable.
As a quick overview:
For 1 casualty point, pin a unit
For casualty points less than the difference between the casualty rating of the unit and its half unit, reduce the unit to a half unit
After that, eliminate a unit
Casualties are applied to the "lowest priority/value" units first. Value is determined by a points system, so a regular infantry British Rifle squad is worth less than a Commando squad. The support weapons also have points, so in general units with support weapons will be affected after units without. Leaders are considered last.
There are other rules involved. For example, passengers cannot be pinned, only reduced or eliminated. And close assaults have their own rules.
Overall, I think the way we've done it is favorable to the player taking the casualties. However, we definitely learned during beta that we have some very smart players. If there are suggestions to improve the process, I'd love to hear them.