Lawyers for homeowners who have been denied mortgage modifications under the Obama administration’s Home Affordable Modification Program make a straightforward argument when they sue banks. As a class-action complaint in Massachusetts puts it, “when a large financial institution promises to modify an eligible loan to prevent foreclosure, homeowners who live up to their end of the bargain expect that promise to be kept. This is especially true when the financial institution is acting under the aegis of a federal program specifically targeted at preventing foreclosure.” Under HAMP, a program funded with $50 billion from the Wall Street bailout, eligible homeowners at risk of falling behind on their mortgages can ask their mortgage servicers for a modification that reduces monthly payments to 31 percent of their monthly income. If they make their monthly payments during a “Trial Period Plan” that’s supposed to last for three or four months, then the modification is supposed to be made “permanent” for five years. Most trial periods drag on for longer than three months, however, and more homeowners have been bounced from the program than have been granted permanent mods.