A federal appellate court in Washington DC will consider the fate of so-called e-cigarettes next month. E-cigarettes use batteries to turn nicotine into vapor. The Food and Drug Administration says it needs to approve the devices before they go to market. But online vendors and even some Seven-Eleven chain stores are defying the agency and selling the product anyway. E-cigarette makers say they can't afford the costs of clinical tests, and FDA regulations would drive their industry underground. Some public health advocates say e-cigarettes may actually be a good way to help smokers wean themselves from the habit. But no one really knows the side effects of the product since they haven't been subjected to rigorous testing.