The Home Valuation Code of Conduct had an unusual origin. It was developed by the New York attorney general, Andrew M. Cuomo, who persuaded the big federal mortgage agencies, Fannie Mae and Freddie Mac, to adopt it. That has effectively made it national policy.

Putting appraisals completely in the hands of lenders may sound like a good idea in principle, because it is supposed to be lenders who are putting their money at risk in a home loan.

But the reality is that many companies that write home loans these days do not have much incentive to worry about the accuracy of appraisals. That is because the companies do not keep the loans on their own books, instead selling them to Fannie Mae or Freddie Mac.

“The code is a formula for continued problems with fraud,” said David Callahan, a senior fellow with the public policy group Demos who has studied appraisals. “Appraisers have been asking for a long time for a reliable firewall between themselves and lenders, and are further from it than ever.”

Appraisers Pressured

Before real estate prices went out of control, appraisal work was straightforward. The appraiser examined a property inside and out, judging it against the prices that similar properties in the neighborhood were fetching. If the appraisal value matched the sales price, the lender financed the loan.

As lending standards collapsed during the housing boom, appraisers were pressured from all sides. When the appraiser did not deliver a satisfactory price, the deal did not get done, and the broker, agent and lender did not get their fees. Homeowners also loved inflated appraisals, using them to take out as much as possible when they refinanced.

“I got daily calls from lenders and brokers saying, ‘Here’s the address. Can you get me $400,000?’ ” said Mr. Kennedy, who has been in the business since 1993.