Fannie Mae has their Code of Conduct posted on their website.
The Wall Street Journal reports that the Federal Housing Finance Agency has imposed a revised code of conduct aimed at preventing mortgage brokers and lenders from pressuring appraisers to inflate their estimates of home values.
Now there is a revised Home Valuation Code of Conduct effective May 1, 2009. According to the news release from the FHFA:
The revised Code builds on existing Fannie Mae and Freddie Mac seller-servicer guidelines to increase the reliability of appraisals for loans sold to the Enterprises for their portfolios or for securitization. The Code applies to lenders that sell single-family mortgage loans to the Enterprises beginning May 1, 2009 and will help assure that borrowers, homebuyers and secondary mortgage market investors receive fair and independent property valuations.