Has natural law theory gradually evolved from apriorism up to empiricism?
Natural law (Britannica):
natural law, in philosophy, system of right or justice held to be common to all humans and derived from nature rather than from the rules of society, or positive law.
It was explained in an answer to another related question that natural law theory was for long aprioristic (for it being based on teleology or theology, cf. Aristotle and Aquinas). I doubt today's natural law is still based on theology, and therefore suppute it has evolved toward a more empirical epistemology.