UA law prof to underwater mortgage borrowers: Ditch your mortgage in good conscience.

White contends that far more of the estimated 15 million U.S. homeowners who are underwater on their mortgages should stiff their lenders and take a hike.

Doing so, he suggests, could save some of them hundreds of thousands of dollars that they "have no reasonable prospect of recouping" in the years ahead. Plus the penalties are nowhere near as painful or long-lasting as they might assume, he says.

"Homeowners should be walking away in droves," White said. "But they aren't. And it's not because the financial costs of foreclosure outweigh the benefits."