15 Though I were innocent, I could not answer him; I could only plead with my Judge for mercy.

Read Job 9:15 Using Other Translations

Whom, though I were righteous, yet would I not answer, but I would make supplication to my judge.
Though I am in the right, I cannot answer him; I must appeal for mercy to my accuser.
Even if I were right, I would have no defense. I could only plead for mercy.