Your business law professor believes that law is "discovered" by humans through the use of reason and choosing between good and evil. she points to the u. s. constitution as an example of her philosophy.
your professor most likely subscribes to which school of philosophy?

The answer is: Ethics or Moral Philosophy

Explanation:

Ethics (or moral philosophy) can be described as the study of morality. This basically establishes that ethical behaviour is good/right. On the contrary, bad behaviour is unethical. It deals with the concepts of right and wrong.

If we read the preamble of the U.S. Constitution:

"We the People of the United States, in Order to form a more perfect Union, establish Justice, insure domestic Tranquility, provide for the common defense, promote the general Welfare, and secure the Blessings of Liberty to ourselves and our Posterity, do ordain and establish this Constitution for the United States of America."

We can basically see a lot of good and ethical intentions. At the time it was written, no other country in the world considered their citizens as highly and respected as the U.S. did.