pro bonopro bono /prəʊ ˈbəʊnəʊproʊ ˈboʊnoʊ/ (also pro bono publico /-ˈpʊblɪkəʊ-koʊ/) adjectiveadj, adverbadv formalLAW used to describe work done by a lawyer or other professional for which they do not charge a payment42% of attorneys surveyed reported doing some pro bono work last year.
Mr. Kunstler is handling the case pro bono.