16 CFR Part 425: "Rule Concerning the Use of Prenotification Negative Option Plans"
Negative option billing should ALWAYS require monthly statements. My health club continued billing my credit card they had on file after I thought I had canceled. Generating via email or regular mail monthly statements would have better alerted me to their practice. Most reputable companies, like PG&E or Blue Cross, keep a credit card on file to be billed, however, they also send customers monthly statements.