What is the term for action chosen when no effective alternative exists?

The term that describes an action chosen when no effective alternative exists is "necessary." This indicates that the action taken is not one of preference or choice but rather a measure that must be undertaken due to the absence of other viable options. In law enforcement and use of force scenarios, this concept is crucial. Officers may find themselves in situations where they must act decisively to protect themselves or others when no other courses of action would suffice to ensure safety or compliance.

"Justifiable" refers to actions that are legally defendable after-the-fact based on the circumstances that were present at the time the action was taken. While this can apply to situations requiring necessary actions, it doesn’t encompass the immediacy dictated by the absence of alternatives.

"Mandatory" implies an obligation to act in a specific way under certain circumstances, which may not always align with the idea of acting when no alternatives exist, as there could be prescribed methods not yet exhausted.

"Optimal" refers to the best possible action given the circumstances, which contrasts with the notion of acting when no other effective alternatives exist. Optimal actions suggest choice and evaluation of best practices, rather than the compelled necessity described by the term in question.