The Military Lending Act was amended in September 2015 to place limits on how high an APR lenders could set for active military personnel. We implemented the new MLA rules just before the deadline.
We allowed lenders to set loan types as MLA-covered through admin pages. Borrowers could be set as MLA-covered by parsing the results of credit pulls from DMS. Using loan type and any included borrower, we derived if the loan itself was covered. The business logic of not allowing loans to be contracted with too high an MAPR was fairly straightforward.
The real difficulty came after realizing the logic surrounding loan products and fees was now lacking. Their inclusion or exclusion affects MAPR values, and thus MLA rules. A refactor was in order due to the fact that these properties can be updated in so many ways across the system.