exculpatory adj 1: clearing of guilt or blame [ant: {inculpative}, {inculpatory}]
mitigating \mitigating\ adj. serving to reduce blame; -- of situations; as, mitigating factors; mitigating circumstances. Opposite of {aggravating}. [Narrower terms: {exculpatory}] Syn: extenuating. [WordNet 1.5 +PJC]
Exculpatory \Ex*cul"pa*to*ry\ Clearing, or tending to clear, from alleged fault or guilt; excusing. "An exculpatory letter." --Johnson. [1913 Webster]