I am interested in the answer to this question from a non-LDS perspective. My personal view, which comes from the LDS perspective is that there are self-existent eternal laws that exist outside of God such as justice, and mercy. Many attributes we ascribe to God would also fall into the category of self-existent and eternal, such as benevolence, perfection, righteousness, and so forth.
The fact that these laws are self-existent and eternal allow for a principle which is likely considered