Since the attempted bombing of a US 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. Chertoff disclosed the relationship on a CNN program Wednesday, in response to a question. An airport passengers’ rights group on Thursday criticized Chertoff’s use of his former government credentials to advocate for a product that benefits his clients. ... In...