Dr. Robert L. Spitzer is a Professor of Psychiatry at the US Columbia University in New York . He is especially known as the chair of the task force of the third edition of the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM-III), released in 1980. In 1973 he argued that homosexuality is not a clinical disorder. As a result homosexuality was declassified from its list of mental disorders. In 2001 Spitzer delivered a paper at The American Psychiatric Association, arguing that "highly motivated" individuals could "successfully" change their sexual orientation from homosexual to heterosexual. The paper was printed in 2003 causing great controversy. It was severely criticised, and although defended by Spitzer, he has raised concerns about the inappropriate ways in which 'ex-gay' and conservative evangelicals have used his research.