(a) The Federal Trade Commission has determined to close its industry-wide investigation of marketing research firms that was initiated in November 1975, to determine if the firms were using questionnaires with invisible coding that could be used to reveal a survey respondent's identity. After a thorough investigation, the Commission has determined that invisible coding has been used by the marketing research industry, but it is neither a commonly used nor widespread practice. Moreover, use of the practice appears to have diminished in recent years. For these reasons, the Commission has determined that further action is not warranted at this time.

(b) However, for the purpose of providing guidance to the marketing research industry, the Commission is issuing the following statement with regard to its future enforcement intentions. The Commission has reason to believe that it is an unfair or deceptive act or practice, violative of section 5 of the Federal Trade Commission Act (15 U.S.C. 45) to induce consumers to provide information about themselves by expressly or implicitly promising that such information is being provided anonymously, when, in fact, a secret or invisible code is used on the survey form or return envelope that allows identification of the consumer who has provided the information.

(c) While the Commission has made no final determination regarding the legality of the foregoing practice, the Commission will take appropriate enforcement action should it discover the practice to be continuing in the future, and in the event that it may be causing substantial consumer injury. Among the circumstances in which the Commission believes that the use of secret coding may cause significant consumer harm are those in which: