CHARLOTTE, N.C. (AP) -- As soaring home prices set the stage for America's great housing meltdown, a critical step in making sure those home sales were a fair deal -- the real estate appraisal -- was undermined from within.

After the nation's last major banking disaster, Congress set up a system to catch rogue appraisers. Their game: inflating the value of homes at the direction of equally unscrupulous real estate agents and mortgage brokers, whose commissions are determined by the size of the deals.

But a six-month Associated Press investigation found that the system is crippled by both the bumbling of its policemen and their inability to effectively punish those caught committing fraud.

And despite ample evidence appraisers are pressured into inflating home values -- sometimes to prices in support of loans that are more than buyers can afford -- the federal regulators charged with protecting consumers have thus far made a conscious choice not to act.

"The system is completely broken," Marc Weinberg, the former acting director at the federal agency charged with monitoring the appraisal industry, told the AP before he retired earlier this year. "It's amazing that the system ever worked at all."

The AP conducted dozens of interviews and reviewed thousands of state and federal documents, and found:

-- Since 2005, at the height of the housing boom, more than two dozen states and U.S. territories have violated federal rules by failing to investigate and resolve complaints about appraisers within a year. Some complaints sat uninvestigated for as long as four years. As a result, hundreds of appraisers accused of wrongdoing remained in business.

-- The only tool federal regulators have to force states into compliance is so draconian -- it would effectively halt all mortgage lending in a state -- that it has never been used.

-- Both state appraisal boards and the federal agency tasked with their oversight are chronically understaffed, many with only one full-time investigator to handle the hundreds of complaints that arrive each year. Some don't even have an investigator.

"The appraisal reforms of the late 1980s were good reforms," said Susan Wachter, a real estate professor at the University of Pennsylvania's Wharton School of Business. "But they were not sufficient to prevent what we have seen ... because regulation without teeth is not regulation."

To be sure, there are many causes of the housing crisis -- lenders who allowed people with spotty credit to buy homes with little or no money down, mortgage brokers who focused on selling loans without regard to the borrowers' ability to repay and investment bankers who bought and sold risky mortgage-backed securities. A few of the worst offenders -- appraisers included -- have been put behind bars.

But experts and industry insiders, including appraisers who feel betrayed by colleagues who don't follow the rules, believe the failure to effectively monitor the real estate appraisal industry contributed to housing's collapse.

This is the way the system is supposed to work:

Typically, an appraiser receives an order from a real estate agent, lender or mortgage broker to inspect a property. Based on a physical inspection of the home and comparable sales in the area, they develop an estimated value for the property. That figure is used by banks to set the home's value as collateral for the mortgage loan.

Appraisers are supposed to come up with a value free of any outside pressure. But more than three dozen appraisers nationwide interviewed by the AP said they often felt pushed by a real estate agent or mortgage broker to fraudulently inflate a property's value. They supplied the AP with documents from lenders asking them to "hit a number."

Documents obtained by the AP also show that hundreds of appraisers complained to federal and state agencies about such fraudulent inflation of property values.

The appraisal system has broken down before. In 1989, Congress concluded that "faulty and fraudulent appraisals were an important contributor to the losses that the federal government suffered during the saving and loan crisis." And it passed the Financial Institutions Reform, Recovery and Enforcement Act.