He is most recognized for his cases against Synanon, a drug rehabilitation group in the 1970s, which attempted to kill Morantz and derail his efforts to rescue members of the group. Since then, Morantz has continued practicing law specializing in the prosecution of those whose victims claim to have been brainwashed. Morantz served as pro bono appellate counsel in Molko vs. Unification Church in 1988, which became the first case where the California Supreme Court recognized brainwashing as a criminal action and allowed victims the right to sue for damages.