The top four banks hold approximately $450 billion in second liens that are supposed to take a backseat to the investors who hold the primary mortgages. But because of the front-seat role big banks play as servicers, they are in a position to put their interests first.

“Unless we can make servicers modify mortgages through bankruptcy or eminent domain, the servicers are not going to reduce principal,” Mr. Miller, 57, said in a recent interview. “Their stance does seem largely driven by accounting concerns — they are trying to maintain the fiction that the mortgages are worth the value they are carrying them at on their books.”

Enter Mr. Miller’s bill, the Mortgage Servicing Conflict of Interest Elimination Act. It bars servicers of first loans they do not own from holding any other mortgages on the same property.

Mr. Miller’s bill has not gained much attention since it was introduced in March. But it ought to, because the Dodd-Frank financial overhaul law is utterly silent on servicer conflicts.

The bill would give these institutions a reasonable amount of time to divest either their servicing businesses or their interests in home mortgages, Mr. Miller said. A likely outcome is that the four biggest banks would spin off their mortgage servicing operations. This would not only resolve the conflict between loan servicers and investors, but it would also result in smaller, less complex banks, he said. That is surely a major benefit.

Another is that Mr. Miller’s law, if enacted, would break up the logjam now thwarting mortgage modifications. “We must reinvent our mortgage finance system,” he said. “This is a huge part of our economy, and we cannot have a healthy recovery with the housing sector as sick as it is.”