[lo_zamoyski]

I don't think exceptions or confined bad side effects make for very good arguments against general policy. You wouldn't ban planes, because sometimes they crash. This isn't math. We're not proving that a rule holds for every element of the domain.

[pjc50]

.. unless you're the person to whom the side effects are happening. How many citizens is it acceptable to wrongly deport or debank, potentially without trial?

[lo_zamoyski]

You have to consider

1. the moral status of the process or parts of the process as such

2. whether the evil of undesirable side effects exceeds the good effects of the policy