Gov. Tom Corbett’s decision last week to permit the medicinal use of a marijuana extract serves the best interests of everyone involved: children with severe seizure disorders, medical researchers, and the residents of Pennsylvania, especially those Pennsylvanians aligned with his Republican Party.

Corbett, a former prosecutor, remains adamantly opposed to the legalization of medical marijuana. His proposal to allow cannabidiol for treatment of severe seizures in children is the lone exception. Its use would be tightly controlled and allowed only for specific diseases.

Corbett’s proposal requires a vote by the Pennsylvania House and Senate before it could become law.

Cannabidiol, or CBD, is an oil derived from marijuana plants. It does not rely on THC — the chemical that gets marijuana smokers high — to effectively treat seizures. Under Corbett’s proposal, cannabidiol would be dispensed at research-based hospitals by medical professionals with experience treating children who have severe seizure disorders or Dravet syndrome, a form of epilepsy.

In October, the federal Food and Drug Administration approved testing of a British pharmaceutical firm’s marijuana-derived drug that is CBD-based and has all of its THC removed — that means it can’t be used to get high.

For several months, a handful of political analysts have predicted the medicinal and recreational use of marijuana could become a political issue nationwide in November’s congressional election. The analysts, speaking in general terms, say Democrats tend to support an easing of restrictions against marijuana, while Republicans generally oppose it, saying the intent of easing restrictions is to allow the recreational use of a potent substance with a reputation as a “gateway” drug — a drug which leads to abuse and addiction to more potent substances.

The analysts’ observations seem to be hold true in the Pennsylvania race for governor, where all four gubernatorial candidates on the Democratic primary ballot have said they favor legalizing marijuana for medicinal use. It’s a popular position with the Baby Boomer generation, a majority of whom at least have tried marijuana and see no reason not to tolerate its legalization.

The scenario already is playing out in several Western states like Colorado, where recreational use is now legal, and California, where marijuana is being grown and marketed for medicinal use. Those states are defying a federal ban on marijuana, apparently with impunity. President Barack Obama and U.S. Attorney General Eric Holder have noted their willingness to work with states that want to decriminalize pot — again, consistent with analysts’ perception of an emerging political issue.

In light of developments in other states, there is wisdom in Corbett’s approach. Introduce one derivative of marijuana for specific treatments and measure its effectiveness. It’s an approach that has won the support of the Pennsylvania Medical Society, whose president, Bruce A. MacLeod M.D., praised Corbett’s decision: “It’s important to have science behind the practice of medicine. Research is needed to carefully evaluate potential new medications. ... Pennsylvania physicians look forward to the pilot results to help improve the care provided to patients who may not have other options.”

At the same time, the decision allows Pennsylvania to observe and benefit from the experience of other states that decriminalize and regulate marijuana use. We can measure its revenue potential as well as unexpected social or legal issues: Is abuse by minors on the upswing? Are school grades dropping or dropouts increasing as a result? Is there an increase in addiction rates involving more potent drugs, or an increase in highway or workplace accidents? What about the rates of clinical depression or other health problems? Is the crime rate rising or falling?

We simply don’t know yet whether Colorado, California and other states have ripped the lid off a Pandora’s Box. There’s no need for Pennsylvania to follow the lead until we know more about the consequences, both short- and long-term.

Meanwhile, the decision to allow cannabidiol strikes a balance between restraint and compassion. Permissible uses can always be expanded later, but it would be much more difficult, once a use it allowed, to repeal it.