So after several rounds on both sides of the table... (being fired and getting laid off / "selectively eliminated"):

- Communicate the bare minimum and hand the person off to an un-involved third party (HR or admin type) to handle the rest of the process. This is not a place for a running debate about the merits of the firing.

- For the sake of the employee, never communicate this on any kind of moralizing basis (eg. you lost this job due to your character failings). They will heal much faster if they can process this as a "lack of fit with the organization". The former can spark some serious self-doubt...

- Either check up on them in a few days (purely personal call) or have a trusted third party check in on them.