The widely renowned literary club of Cincinnati, which he joined in 1850, and of which he remained an active member for eleven years, awakened his social sympathies and ardent interest. To the reading of essays, and to the discussions on political, social, and moral questions, he always listened, and in the latter often took part. In debate, he was strong, eager, clear, and logical. He had an aptitude at seeing principles and getting at the kernel of questions. Among those who during these years participated in the social or literary entertainments of the club-room were Chief Justice Chase, Thomas Corwin, Thomas Ewing, father and son, General Pope, General Edward F. Noyes, Stanley Matthews, M. D. Conway, Manning F. Force, W. K. Rogers, John W. Herron, D. Thew Wright, Isaac Collins, Charles P. James, R. D. Mussey, and many others of ability and distinction. In January, 1852, the opportunity for "getting a start" in his professional career came. While making a sensible, energetic little speech in behalf of a criminal indicted for grand larceny, named Cunningham, he attracted the attention and won the commendation of Judge R. B. Warden, then president judge of the criminal court, who thereupon appointed the modest young attorney counsel for Nancy Farrer, whose case became the great criminal case of the term, if not of the times.
Nancy Farrer had poisoned all the members of two families. She had a bad countenance, a sinister, revolting look. It is not strange that she should have been considered by the court and jury that tried her, and by the entire public, a qualified candidate for the gallows. Hayes, in defending his client, had to contend against the passions, the indignation of the public, and the predispositions and prejudices of judge and jury. The judge who tried the case was not the one who appointed the comparatively unknown attorney as counsel. Hayes saw instinctively the immense importance of the case, and knew intuitively that a crisis had come in his career. He set laboriously to work to establish an impregnable line of defense.
He found on examination of the proofs that the supposed murderess was totally irresponsible, because of hereditary idiocy and insanity. Her father had died of drunkenness in a Cincinnati hospital, and her mother went about under the insane hallucination that she was a prophetess. Nancy's conduct and conversations while employed in the wholesale poisoning business showed that she had no moral comprehension of what she was about. But the plea of insanity had been so often and so vehemently pressed in defense of prisoners who were sane that it seemed to be of no avail in defense of one who was not. The cry of insanity, like that of "wolf," had been so repeatedly raised when there was no insanity, that it was not heeded when there was. Notwithstanding an argument which for legal learning and forensic eloquence attracted the attention of the press and bar, and established the counsel's reputation, the poor, insane idiot was convicted of murder in the first degree. Hayes at once obtained a writ of error, which the district court reserved for decision in the Supreme Court of the State. The case was argued and determined in that court at the December term, 1858, and reported in 2 Ohio St. Reports. R. B. Hayes appeared for plaintiff in error, and George E. Pugh, attorney-general for the State. The earnest and determined advocate of Nancy Farrer carried his points, obtained a new trial, and greatly enhanced his professional reputation. The then official reporter of the Supreme Court of Ohio, who heard this argument, says: "It was a truly admirable effort, and the peroration was indescribably pathetic. But on this occasion, as on all others, Mr. Hayes was singularly modest." Although a new trial was granted, through the concurring opinions of Justices Corwin, Thurman, and Ranney, Nancy Farrer was never again tried. She was sent to a lunatic asylum.