Definition is not by 'domus', but by assailant..
Excluded are a significant group of possibly the most extremely vulnerable, helpless, unable to escape and rehouse themselves .
They can N O T go to women's refuge, because the assailant who attacks them is inside in their existing home, but is not inside the correct tick box which officials imagined when devising the definition.
Only those with personal relationships ever share a roof, in that imagined world.
Deemed to be either non-existent, or else to be magically immune from abuse in their homes, are; flatsharers, sofa surfers, below-radar sub-tenants, desperate people including elderly and disabled and stalked women and any who may N O T be immigrants but who nevertheless have the choice of sleeping rough, or accepting every form of DV listed in the new law.
Once, a Judge did rule that non-standard situations, including flat sharing, might make people liable to D.V.. I can't find the case, and it has since been applied only in processing housing benefit claims, for councils accepting that someone has not made herself 'intentionally homeless ' by fleeing D.V. by an unrelated housesharer.
That ruling, though, does not give her access to A N Y of the D.V. services such as collecting essential personal belongings, photographing injuries, accompanying to hospital, and, above all, any sanctuary roof over her head, or legal expert advice on injunctions, or follow up services. D. V. agencies check the list of 'correctly defined assailants', spot that someone living under the same roof is the 'wrong' attacker, and will not even give comfort or advice. Legally, they believe, housesharers' attacks of any type are merely civil 'neighbour disputes '.