The Food and Drug Administration is in charge of regulating drugs in California and all across the United States. To do so, they must first research these drugs to determine what needs to be done in terms of allowing or disallowing their use or in regulating that use.
The first step is to test the drugs. This often begins with animal trials but will also involve human trials. The lab tests must be done first, and then the findings are considered before the drug is allowed to be given out in human trials. It will most often not be approved for public use until the conclusion of all three. There are three separate phases that are used during these human trials.