The value of marijuana as a pain-management medication is still unclear as the government continues to discourage research into the effects of the drug, according to a pair of news items.

Fewer than 20 clinical trials have been performed investigating the potential benefits of smoking marijuana, The Wall Street Journal reported. What’s more, the number of participants—roughly 300 between all the studies—is far too small to generate enough evidence to promote the drug’s use. Other researchers who aim to unlock the possible pain-managing effects of marijuana have run into federal roadblocks, including resistance from the Drug Enforcement Agency, and reluctance on the part of the government to allow researchers to grow their own crops, according to a New York Times article.

The DEA has hampered pain management efforts in the past, affecting nursing homes across the country. The agency has recently begun more heavily enforcing rules that require written approvals from doctors. Many nursing home nurses view these and other rules from the DEA as a hindrance to their efforts at relieving pain among their patients.