Details are murky, but Senator Dodd appears to want to spend many billions on a new federal agency to buy-up undefined “distressed” mortgages at less than their original value.

Suppose Mr. Jones has a $300,000 mortgage on a house now worth $250,000. The new agency would offer to pay off the loan for $250,000 and then let Jones stay in the house with a new $250,000 mortgage that would then be guaranteed by the Federal Housing Authority (which ultimately means the U.S. taxpayer). FHA would debase its customary lending standards.

If banks and mortgage service companies are willing to write-off a large part of the value of some mortgages, why would we need to put U.S. taxpayers at risk? Why couldn’t each borrower simply negotiate a new contract, as hundreds of thousands have already done (though usually for a lower interest rate rather than forgiveness of principal).

If a home owner or speculator like Mr. Jones could get a smaller mortgage through a government agency by not making payments and threatening to default, that would create a huge moral hazard. His neighbors would resent his special treatment, and threaten to default on their loans too.

Since everyone would rather have a smaller mortgage than a larger mortgage, there would be rationing problem of deciding who is or is not worthy for such special treatment. Such priorities are likely to be based on political considerations rather than sensible economics or risk management.

Since Mr. Jones is already seriously delinquent on the current mortgage, he may well have a history of not paying other bills and therefore a poor (subprime) credit rating. There is no good reason to expect that he will not also default on the new FHA mortgage. Risky loans still remain risky, but because of the FHA guarantee that risk would be shifted to taxpayers.

This scheme would convert a localized mortgage problem into a national mortgage scandal.