If we want good immigration policies psychologists are going to be busy with Gould's cultural disorder hypothesis. I haven't seen anything else that takes the problem of imported group psychopathology on adequately. The good news is that some minor tweaks to social psychological and cultural psychological theories--coupled with some cleverly developed and deployed short-form psychometric instruments--will likely do it.
There will be:
1. Pre-vetting. The cultural psychology---including personal cultural psychology--of the persons considered for emigration will have to be pre-analysed using appropriate instruments and parameters, with an emphasis on mental health according to practically applicable diagnostic criteria. (ICD-11 style dimensional criteria may be too difficult to apply, and categorical approaches may be unavoidable for the sake of efficiency/practicality.)
(I suggest that personal-cultural psychology maps to the person's dispositional attitudes as imbued by the cultural narratives they were immersed in during developmental phases and the adaptive and maladaptive early schemas that resulted from that.)
2. Corrective deprogramming with sign off. This is the complicated part as it will likely be expensive. The bottom line is that assimilation needs to be ensured by psychoeducation with sign-off. Things like rape culture can't be left to chance. The individual needs to be counselled, educated, and required to pass a test before admission, and if there is an immovable personal-cultural disorder or psychopathology, then emigration cannot be approved.
At minimum 2 is likely to require a battery of new short form psychometric instruments--or at least a suite of existing ones--which can be applied with relative ease and limited expense.
The overarching problem, of course, is: How does one suppress maladaptive schemas and personal cultural narratives which have been developed since childhood and likely involved trauma and abuse with a brief counselling, psycho-education, and evaluation procedure?
