What is the primary use of a declarant’s state of mind if not offered for its truth?

The primary use of a declarant’s state of mind when not offered for its truth is to demonstrate evidence of insanity. In legal contexts, this can be particularly relevant in cases where a person's mental state at a particular time is a significant factor, such as in criminal cases where a defendant may be claiming that they were not able to understand the nature of their actions due to mental illness. The statement reflects the individual's mental condition and can help establish the presence or absence of insanity at the time of an event.

While other choices might seem relevant in different contexts, they do not accurately capture the primary intent behind using a declarant's state of mind in this scenario when truth is not being contested. Statements cannot be used simply to prove their content or establish contractual agreements, as these communications become relevant primarily through their impact on the declarant's understanding and perceptions rather than for determining factual accuracy.