1) Court psychiatrist 2) Expert in a sanity trial 3) Head-shrinker 4) Old-timey psychiatrist 5) Psychiatrist 6) Shrink 
Alienist is an archaic term for a psychiatrist or psychologist. Despite falling out of favor by the middle of the twentieth century, it received renewed attention when used in the title of the 1994 novel The Alienist by Caleb Carr. Although currently not often used, the term `alienist` is still used in psychiatric hospitals to describe those men.....
• (n.) One who treats diseases of the mind.
Al'ien·ist noun [ French aliéniste .] One who treats diseases of the mind. Ed. Rev. 
Alienist: The term 'alienist' was heading for obsolescence until it was returned to a position of some prominence by the 1994 book 'The Alienist' by the historian/novelist Caleb Carr. The story of 'The Alienist' starts In New York City in March 1896 when reporter John Schuyler Moore is called to the East River by his old Harvard classmate and frien...
[n] - a psychiatrist and specialist in the legal aspects of mental illness
noun a psychiatrist and specialist in the legal aspects of mental illness
(formerly) a doctor specializing in the treatment of mental illness. · an expert witness in a sanity trial.