The type of investigations, including clinical investigations, that must be conducted by a new drug sponsor to demonstrate that a new drug is effective. As amended in 1962, the Federal Food, Drug, and Cosmetic Act requires that drug sponsors provide substantial evidence of effectiveness and gives this term a special definition: ”evidence consisting of adequate and well-controlled investigations, including clinical investigations, by experts qualified by scientific training and experience to evaluate the effectiveness of the drug involved, on the basis of which it could fairly and responsibly be concluded b}’ such experts that the drug will have the effect it purports or is represented lo have under the conditions of use prescribed, recommended, or suggested in the labeling or proposed labeling thereof” (section 505(d) of the Act). FDA rubs further delineate the types of studies which must be conducted to satisfy this requirement, and permit waiver in certain cases. The study protocol must minimize bias and must assure comparability between test and control groups. Generally, four types of control are recognized: comparing treated and untreated patients^ comparing results of new drug use with a placebo, comparing results of new drug use with results from a regimen of therapy known to be effective, and comparing results of new drug use with experience that is historically derived. The statute and regulations do not explicitly require that safety of a new drug be established by adequate and well-controlled studies; nor do they set forth explicit criteria for safety testing.