Since the attempted bombing of a U.S. airliner on Christmas Day, former Homeland Security secretary Michael Chertoff has given dozens of media interviews touting the need for the federal government to buy more full-body scanners for airports. What he has made little mention of is that the Chertoff Group, his security consulting agency, includes a client that manufactures the machines. An airport passengers' rights group ... criticized Chertoff, who left office less than a year ago, for using his former government credentials to advocate for a product that benefits his clients. Mr. Chertoff should not be allowed to ... privately gain from the sale of full-body scanners under the pretense that the scanners would have detected this particular type of explosive," said Kate Hanni, founder of FlyersRights.org, which opposes the use of the scanners. Chertoff's advocacy for the technology dates back to his time in the Bush administration. In 2005, Homeland Security ordered the government's first batch of the scanners. Today, 40 body scanners are in use at 19 U.S. airports. The number is expected to skyrocket at least in part because of the Christmas Day incident. The Transportation Security Administration this week said it will order 300 more machines.