[2] Until his retirement in 2015, he was lead clinician at the Neuropsychiatry and Memory Disorders Clinic at St Thomas' National Health Service teaching hospital in Central London.
[3] From 1989 to 2015, Kopelman was first a consultant neuropsychiatrist, then professor of neuropsychiatry at Guy's, King's and St Thomas' School of Medicine.
[3] In 2020, Kopelman served as a defence expert on behalf of WikiLeaks founder Julian Assange at his first extradition hearing.
Delivering her verdict in January 2021, district judge Vanessa Baraitser ruled that Assange could not be extradited from the UK to the U.S. because of fragile mental health and risk of suicide.
"[8] During the hearing, prosecution lawyers questioned Kopelman's impartiality as an expert witness, asserting he had failed in his duty by deliberately concealing the information that, during his time at the Ecuadorian embassy, Assange had formed a long-term relationship with Stella Morris and fathered two children with her.
"Professor Kopelman's decision to conceal their relationship was misleading and inappropriate in the context of his obligations to the court," Baraitser wrote, "but an understandable human response to Ms. Morris's predicament."