There is a well known rule that if A is threatening B's life, B may kill A, if necessary, to prevent that.
Is there any such rule in non-capital cases? Specifically:
- If A is threatening B with physical injury, can B injure A to prevent it?
- If A is threatening B with monetary harm, can B financially injure A to prevent it?
If so, then:
- Does B's injury of A have to be proportionate to what A would have otherwise done? For example, if A is seeking to inflict $100's worth of damage on B's possessions, can B, to prevent that, inflict $100's worth of damage on A's? $100.25's worth? $1,000,000's worth? Likewise, if A is seeking to damage B's person to a certain degree (monetary degree in terms of nezek, or to some degree as defined by some other standard), can B damage A to the same degree? to a higher degree?
- Would B have any liability to A thereafter (in bes din)?
Of course, for practical guidance in any specific case, each person should consult his rabbi; this question is about general rules.