In the fall of 1850, the College of Physicians and Surgeons in the City of New York (P&S, later to become Columbia’s medical school) expelled a student named James Parker Barnett for purportedly having “African blood flowing in his veins,” even though Barnett had been attending P&S for two years! What had P&S administrators learned about Barnett?

In the racial environment of antebellum New York, such discrimination might have passed unnoticed. But James Parker Barnett’s father refused to accept his son’s expulsion without a fight...