Discovery of new psychiatric medication, whether for the treatment of depression, autism or schizophrenia, is at a virtual standstill. As just one example, the antidepressants on the market today are no more effective at reversing the mood disorder than those that first became available in the 1950s.

New thinking is desperately needed to aid the estimated 14 million American adults who suffer from severe mental illness. Innovation would likely accelerate if pharmacologists did not have to confront an antiquated legal framework that, in effect, declares off-limits a set of familiar compounds that could potentially serve as the chemical basis for entire new classes of drugs.

LSD, ecstasy (MDMA), psilocybin and marijuana have, for decades, been designated as drugs of abuse. But they had their origins in the medical pharmacopeia. Through the mid-1960s, more than 1,000 scientific publications chronicled the ways that LSD could be used as an aid to make psychotherapy more effective. Similarly, MDMA began to be used as a complement to talk therapy in the 1970s. Marijuana has logged thousands of years as a medicament for diseases and conditions ranging from malaria to rheumatism.

National laws and international conventions put a stop to all that. The Controlled Substances Act of 1970 declared that these drugs have “no currently accepted medical use” and classified them in the most stringently regulated category of controlled substances: Schedule I. The resulting restrictions create a de facto ban on their use in both laboratories and clinical trials, setting up a catch-22: these drugs are banned because they have no accepted medical use, but researchers cannot explore their therapeutic potential because they are banned. Three United Nations treaties extend similar restrictions to much of the rest of the world.

The decades-long research hiatus has taken its toll. Psychologists would like to know whether MDMA can help with intractable post-traumatic stress disorder, whether LSD or psilocybin can provide relief for cluster headaches or obsessive-compulsive disorder, and whether the particular docking receptors on brain cells that many psychedelics latch onto are critical sites for regulating conscious states that go awry in schizophrenia and depression.

In many states, doctors can now recommend medical marijuana, but researchers cannot study its effects. The uneasy status quo leaves unanswered the question of whether the drug might help treat attention-deficit hyperactivity disorder, nausea, sleep apnea, multiple sclerosis and a host of other conditions.

A few privately funded studies of these compounds have yielded tantalizing hints that some of these ideas merit consideration. Yet doing this research through standard channels, as psychopharmacologist David J. Nutt of Imperial College London and his co-authors noted in a recent article in Nature Reviews Neuroscience, requires traversing a daunting bureaucratic labyrinth that can dissuade even the most committed investigator. (Scientific American is part of Nature Publishing Group.) It can take years to receive approval for a clinical trial from both regulators and hospital ethics committees, even while tallying thousands of dollars in licensing fees and tens of thousands to obtain drugs that are, of course, unavailable from a chemical supply catalogue.

The endless obstructions have resulted in an almost complete halt in research on Schedule I drugs. This is a shame. The U.S. government should move these drugs to the less strict Schedule II classification. Such a move would not lead to decriminalization of these potentially dangerous drugs—Schedule II also includes cocaine, opium and methamphetamine, after all—but it would make it much easier for clinical researchers to study their effects.

If some of the obstacles to research can be overcome, it may be possible to finally detach research on psychoactive chemicals from the hyperbolic rhetoric that is a legacy of the war on drugs. Only then will it be possible to judge whether LSD, ecstasy, marijuana and other highly regulated compounds—subjected to the gauntlet of clinical testing for safety and efficacy—can actually yield effective new treatments for devastating psychiatric illnesses.