Not many parents would encourage their 11-year-old child to take an illegal drug, but that is exactly what Harvard University psychiatrist Lester Grinspoon urged his son to do. The drug? Marijuana. The reason? Grinspoon’s son was terminally ill with leukemia, and Grinspoon was desperate to try anything to reduce his suffering.

Grinspoon had originally become interested in researching marijuana because he wanted to prove it had no legitimate medical application. Instead, he watched the drug transform his son’s last months, making them tolerable by lessening the pain and nausea of chemotherapy. The experience convinced Grinspoon to spend much of his remaining career researching the benefits of medicinal marijuana and advocating for its use.

“Most doctors have allowed themselves to become quite ignorant about cannabis,” Grinspoon said. “They have been brainwashed like just about everyone else in this country that marijuana is a terrible substance.”

The U.S. government’s classification of marijuana as a Schedule I controlled substance makes it a federal offense to possess or distribute it for any reason — even medicinal ones, regardless of varying state laws. Sixteen states and the District of Columbia allow marijuana to be prescribed for medicinal use, but the federal ban on possession has impeded efforts to make pot available by prescription. This has created a bizarre system in which select “medicinal marijuana doctors” profit from liberally awarding prescriptions while most doctors are too hesitant to even study its potential benefits.

California and Colorado have the most liberal policies; in both states, it is not difficult to acquire a medicinal marijuana prescription even for patients with minor symptoms, such as back pain or PMS. But in the states with more restrictive policies, such as New Jersey, the laws are so strict it is even difficult for patients in extreme pain to receive prescriptions.

Despite the trend toward liberalization among the states, the Obama Administration seems resolved to uphold the current hard-line policy. “Marijuana use is associated with addiction, respiratory and mental illness, poor motor performance, and cognitive impairment,” the White House’s website states, adding that the science is “still evolving in terms of long-term consequences of marijuana use.”

But some doctors argue that legalization is exactly what is needed for the science to be clarified. Right now, it is only legal for physicians to research medicinal marijuana if they are doing so as part of a “federally approved clinical trial,” according to the National Institute on Drug Abuse. This restriction has stunted research on the drug, according to the California Medical Association, which in October 2011 became the first group of physicians to make a public call for the full legalization of marijuana. The association noted that the current laws have made it impossible to determine scientifically whether marijuana should be seen as a medicine or harmful illicit substance.

There is already solid evidence that marijuana effectively reduces pain, suppresses nausea and stimulates appetite in some patients. The most common medical application of marijuana is to relieve the painful side effects that come with AIDS and cancer treatments. Because the drug is frequently smoked, however, it can introduce toxic combustion to the lungs. Marijuana is also associated with the psychological effect of being “high,” which is potentially addictive — a cause for concern in users who are not already terminally ill.

The lack of conclusive evidence on the risks and benefits of marijuana makes it irresponsible for doctors to prescribe it, asserts Joel Hay, professor of pharmaceutical economics and policy at the University of Southern California. “No reputable physician will risk the federal sanctions and lack of scientific validity to illegally ‘prescribe’ medical marijuana,” Hay wrote in an email.

In California and Colorado, the doctors who prescribe make upwards of $200 per five-minute interview, Hay wrote. As a result of their liberal prescriptions, he added that he assumes “98 percent of those using ‘medical marijuana’ are using it as a smoke screen for [the patients’] recreational use.”

Because Grinspoon does not consider recreational marijuana use unhealthy, the Harvard psychiatrist said he is not medically concerned about its overprescription, but he added that he does “detest the idea from a moral point of view” because certain doctors profit so greatly.

Mikey Goldsmith, who was diagnosed with metastatic lymphoma two years ago and has had a marijuana prescription since moving to Colorado, said he easily received his prescription from a traveling medicinal marijuana doctor after deciding independently that the drug could help him.

In his years battling cancer, “not one doctor” suggested that he consider using marijuana to relieve many of the side effects from his cancer treatment, Goldsmith said. “They said ‘you have cancer, let’s fix that.’”

He now uses marijuana to relieve pain, substituting it for the pain-reliever Percocet he was prescribed after undergoing surgery to remove the cancer. Goldsmith said Percocet had harsher side effects than marijuana. Percocet “caused me constipation for four days — and that’s not OK with me,” he said.

Doctors are reluctant to prescribe marijuana, even where it’s legal, in part because of the way they’re trained, argued Grinspoon. The major pharmaceutical manufacturers have an outsized influence on medical education and will never support cannabis therapy because they “can’t patent a plant,” he added.

Despite the reluctance by many physicians to prescribe it, the California Medical Association is not only advocating for the legalization of medicinal marijuana; they also support the federal legalization of recreational use. Full legalization will likely cause it to be more readily researched and accepted. Additionally, the “CMA recognizes there is a public movement toward legalization of marijuana,” read the CMA’s appeal.

Many Americans agree. A Gallup poll released in October found that 50 percent of Americans — the highest percentage yet — believe that marijuana use should be legalized. Older polls have found that a full 73 percent of Americans support legalization of medicinal marijuana to reduce patients’ pain and suffering. Several state governors also recently petitioned the federal government to reclassify the drug so it could be used medically.

According to Grinspoon, the current laws will continue to “put people in this position to get it illegally or from a doctor who isn’t doctoring … It has to change.”