16 CFR Part 425: "Rule Concerning the Use of Prenotification Negative Option Plans"
I subscribed to one year of net detective. I soon got an e-mail offering me a free upgrage to a better version. I deleted that e-mail without opening it, since I wasn't interested in any upgrade. Unknown to me, if you didn't refuse the upgrade, they would automatically enroll you at a price of 29.95 per month. I only realized what had happened when my credit card got a $29.95 charge. When I called Net Detective, they said I hadn't refused their offer and was obligated to a year at 29.95 per month.