The Humane Society says the vast majority of ivory items placed for sale are explicitly illegal and most often come from poached African or Asian elephants. The animals are all considered threatened or endangered; more than 20,000 are killed for their ivory every year.

Another animal rights group, the , Tuesday called "Killing for Keystrokes." The study details the growing issue of Internet-driven ivory trade and suggests the United States is responsible for more than two-thirds of the worldwide exchanges -- more than 10 times the amount of any other nation. The IFAW says it plans to "strictly monitor eBay" to make sure its new regulation is enforced.