moral minimum

noun2

1. •
   A standard or principle upheld as indispensable for moral conduct, whether within a particular context or in general.

   • John Stuart Mill . . . was not long in proving that the moral minimum of wages was a myth. — 1887
2. •
   The specific rule that one should do no intentional harm, often considered the bare minimum required for ethical behavior.

   • First, consider the moral minimum, do no harm. — 2005