A person who is expert in or given to casuistry.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "casuist" in a sentence
"If the ascetic moralist was a quasi - mathematician, the casuist was a kind of medical man."
""But tell me, Tribune, you who are a notable casuist, which is the best for a state -- that its governor should be over-thrifty or over-lavish?""
"The casuist may therefore cherry pick his route to his destination."