The new head of the Drug Enforcement Administration on Wednesday finally acknowledged what his predecessor could not, admitting that "heroin is clearly more dangerous than marijuana."

Chuck Rosenberg's comments, reported by the Huffington Post's Matt Ferner, came a week after he stated that marijuana is "probably" less dangerous than heroin, inspiring some criticism and mockery from media. "If you want me to say that marijuana's not dangerous, I'm not going to say that because I think it is," Rosenberg said last week, according to US News's Steven Nelson. "Do I think it's as dangerous as heroin? Probably not. I'm not an expert."

Rosenberg's original answer was akin to politicians saying they're not scientists when asked if global warming is real. You may not be a scientist or an expert, but there is plenty of data and research out there to let you — a smart, thinking human being — decide what the facts are.

In the case of marijuana versus heroin, the DEA chief didn't need a "probably" in his statement: Marijuana is clearly safer than heroin. Marijuana's biggest risk is the possibility of dependency, which can cause the drug to take over someone's life to the point that he or she is constantly impaired. Heroin can not only take over someone's life (and at much higher rates than marijuana), but it poses a high risk of overdose death that marijuana does not. Both drugs can also cause accidents, although the research suggests heroin is slightly worse on this front as well.

Given the clear empirical evidence, it might seem strange that DEA chiefs are consistently asked about which drug is more dangerous. Can't reporters just use Google to find out which drug is worse?

But this question comes up all the time for the DEA — as it also did for Rosenberg's predecessor, Michele Leonhart — in part due to a widely misunderstood aspect of US drug policy. Marijuana and heroin are both considered schedule 1 substances — the strictest drug classification — by the federal government. Many people, reporters (but not US News's Nelson), and even the DEA misinterpret this to claim that the feds think pot and heroin are equally dangerous. But that's not what the scheduling system says at all.

Marijuana and heroin are schedule 1 drugs, but that doesn't say anything about whether the feds think they're equally dangerous

Schedule 1 is the strictest classification in the federal government's drug classification system, but the category is not solely about a drug's risk. The schedule is also for drugs that have no medical value, but aren't ranked by risk of abuse. Schedule 2 to 5 drugs are substances that have at least some medical value, and they are numerically ranked by risk of abuse.

It may be helpful to think of the scheduling system as made up of two distinct groups: nonmedical and medical. The nonmedical group is the schedule 1 drugs, which are considered to have no medical value and high potential for abuse. The medical group is the schedule 2 to 5 drugs, which have some medical value and are numerically ranked based on abuse potential (from high to low).

The federal government reasons that nonmedical drugs should be more restricted, since they can't be allowed even for doctors. The schedule 2 drugs have about the same level of restrictions — although they're easier to obtain for medical purposes, including research. Schedule 3 and lower are where the restrictions begin to really drop.

Whether you agree that marijuana has no medical value is certainly up for debate. The latest studies suggest medical pot has a lot of potential, and a review of the drug's schedule is currently underway. But even at schedule 1, the feds don't really consider marijuana equally dangerous to heroin — regardless of what the DEA chief says.

VIDEO: Weed is not more dangerous than alcohol