Libman was educated in the New York public school system. He received his B. A. from the City College of New York in 1891 and was graduated from the Columbia College of Physicians and Surgeons in 1894. For the next two years he served his internship at Mount Sinai Hospital in New York City. There he came under the guidance of the eminent diagnostician Edward G. Janeway and the influence of pediatricians Abraham Jacobi and Henry Koplik. Libman spent the years 1896-1897 studying in Berlin, Munich, Vienna, and Graz. In the laboratory of the noted bacteriologist Theodor Escherich, he studied infant diarrheas, which led him to the discovery in 1898 of the causative organism Streptococcus enteritis.
Libman became an assistant pathologist at Mount Sinai Hospital in 1897 and associate pathologist in 1898, a position he held until 1923. In addition, he was appointed adjunct physician in 1903 and promoted to attending physician status a decade later. He was a consulting physician from 1925 until his death. From these positions, Libman was able to coordinate his clinical and laboratory studies, expanding each discipline by association with the other. He continued his work on streptococci and published studies on pneumococci, meningococci, typhoid, paracolon, and pyocyaneus infections. Through this research, which required the incorporation of blood into bacteriologic media, he became interested in blood cultures and did the first extensive clinical studies on blood transfusions, a form of medical treatment then in its infancy. Continued interest in blood cultures and heart disease culminated in Libman's classic descriptions of subacute bacterial endocarditis, an infection, generally of a heart valve, which usually has an insidious onset and protean symptoms. His important papers include the 1912 recording of six cases of coronary artery thrombosis (an entity not then recognized), studies on sprue and pernicious anemia, and a notable presentation on otitic infections.
Libman's observations of suffering patients led to his development of a new test for sensitivity to pain. In 1923-1924, along with Dr. Benjamin Sacks, he isolated a form of endocarditis which he called "atypical verrucous endocarditis"; it is now known as Libman-Sacks disease. Most of his published papers reflect clinical problems studied in the laboratory. His interest in cardiology and postgraduate medical education encouraged physicians to seek appointments under his directorship, effecting what Dr. William H. Welch termed "the Mount Sinai School of Cardiology. "
Libman helped organize the Graduate Fortnight (a series of lectures and seminars) of the New York Academy of Medicine, and in 1931 he presented its first symposium on diseases of the heart. Other formal expressions of his interest in medical education include the endowment of the Noguchi Lectureship at the Medical History Institute in Baltimore, the Herbert Celler Fellowship Fund, the William H. Welch Lectureship at Mount Sinai Hospital, and the Humphry Davy Rolleston Lectureship at the Royal College of Physicians in London. Although he contributed personally to these fellowships and lectureships, he was also active in raising funds for them. He was chairman of the board of the Dazian Foundation for Medical Research, established by a former patient in appreciation of Libman. The legacy he left to the Tuskegee Institute of Alabama is indicative of his humanitarianism.
He also served on the board of governors of the Hebrew University in Jerusalem, was vice-president of the American Friends of the Hebrew University, and was on the executive committee of American Jewish Physicians. He was president of the New York Pathological Society in 1907. Emanuel Libman died in the Mount Sinai Hospital following a short illness; funeral services were held at the Free Synagogue.
Dr. Libman had an abiding interest in Judaism.
He was a member of many medical organizations.
Libman led an eccentric and solitary life. He often worked 20 hour days, was devoted to his students, and was a stimulating teacher in an era when a flair for the dramatic or flamboyant in teaching style was in vogue.