The federal laws that regulate use of biological control agents in the USA are complicated because none was designed to deal with importation of biological control agents. Importation of living biological control agents into the USA almost always requires a federal permit and may require a "wildlife" collection and/or export permit from the exporting country. State laws can be simpler: importation of living biological control agents into Florida always requires a state permit. Decisions whether or not to issue importation permits for any particular species are made after evaluation by scientific committees of importation applications. For importation of classical biological control agents, such permits are needed for importation into quarantine facilities for screening, and then a second set of permits is required for release into the field. The federal and state laws are in place to ensure safety to the environment, to non-target species, to agriculture and to human health, and to ensure compliance with the "wildlife" laws of exporting countries.
Classical biological control was first practiced in the USA in the late 19th century, at a time when there were no regulations. The regulations became progressively more stringent as biological control developed from an art into a science. The first biological control attempts were made at a time when surgery in the USA was performed without anesthesia and without antiseptic methods. Some things were done in the early days of biological control which would not now be permitted. For example, the Indian mongoose (Herpestes javanicus) was imported into Jamaica, Barbados, and Hawaii to control rats that caused heavy losses to sugarcane growers, and the marine toad (Bufo marinus) was imported into Puerto Rico and Australia to control scarab beetle larvae (white grubs) that also damaged sugarcane. These non-specialized predators threaten populations of non-target organisms. At the time, an environmentally less aware era, protection of the crops may have been the only consideration. People who criticize biological control often bring up these examples in attempt to show that biological control is not safe. We could equally argue, with the same kinds of data, that surgery is not safe because many people in the last century died during or after it. Yet, even the early days of biological control had some spectacular successes which controlled devastating pests without causing environmental damage.
Now, biological control practitioners work with specialized natural enemies that attack the target pest only, or the target pest and a few of its very close relatives. If those close relatives are likewise pests, no harm is done. If those close relatives do not occur where the biological control agent is released, no harm is done. If those close relatives are minimally attacked (the biological control agent having a much more deleterious effect on the target), little harm is done, and the balance sheet may justify use of the biological control agent because this causes less damage than would any other action (including the action of taking no action to control the target). The biological control practitioner's code of ethics now resembles that of surgeons: do no harm.