Law360, New York (October 13, 2015, 4:33 PM EDT) -- The filed-rate doctrine is a century-old common law doctrine that requires entities that are required to file tariffs to adhere strictly to those terms. The purpose of the doctrine is to appropriately forbid regulated entities from charging rates other than the one on file with the appropriate state or federal regulatory authority, but a few courts have extended this doctrine to insulate defendants from alleged illegal conduct. The Second Circuit Court of Appeals recently held that the filed-rate doctrine applied to bar all claims by GMAC mortgagors against Balboa Insurance Co., the insurer that contracts with GMAC to provide lender-placed or force-placed insurance to cover lapses in homeowners' voluntary coverage for the mortgage servicer. In Rothstein v. Balboa Insurance Co., 794 F.3d 256 (2d Cir. 2015), the court held that the plaintiffs' claims offended both the nonjusticiability principle and the nondiscrimination principle underlying the filed-rate doctrine because Balboa's rates for LPI were filed with state regulators and GMAC had invoiced borrowers for the amount that GMAC had initially paid Balboa for the insurance coverage....