Breaching principles of natural law, rectitude, or justice, and so inconsistent with the demands of virtue, purity, or "good morals"; not right, not moral. (Compare unethical, illegal.)
irreproachable
adj
Free from blame, not open to reproach or criticism; blameless.
How often have the words immoral and irreproachable occurred in a corpus of books? (source: Google Ngram Viewer )