1703, in ethics, "the solution of special problems of conscience by application of general principles or theories;" see casuist + -ry. Even in the earliest printed uses the sense was pejorative.
Entries linking to casuistry
casuist n.
c. 1600, "one who studies and resolves cases of conscience," from French casuiste (17c.) or Spanish casuista (the French word also might be from Spanish), Italian casista, all from Latin casus "case" (see case (n.1)) in its Medieval Latin sense "case of conscience." Often since 17c. in a sinister or contemptuous sense "over-subtle reasoner, sophist." Related: Casuistic; casuistical; casuistically.