Republican presidential candidates have spent much of their time on the campaign trail lately pledging more treatment and less punishment to deal with epidemic drug abuse, most dramatically in a viral video featuring an emotional New Jersey Gov. Chris Christie. This is a welcome development — even if the GOPers, like their Democratic counterparts, exaggerate the degree to which arrests for simple possession of drugs, as opposed to trafficking, have swollen the prison population. The more attention leaders focus on the heartbreaking rise in prescription opioid and heroin addiction and on overdose deaths, the better.

According to Drug Enforcement Administration data, the candidates are raising their voices at a time when federal and state policy has already begun to shift — and to show results.

This country's 21st-century drug abuse problems have been rooted in legal drugs rather than illegal ones: specifically, massive diversion and abuse of prescription opioid painkillers, which led to a spinoff rise in abuse of chemically similar heroin. The DEA's freshly issued National Drug Threat Assessment Summary shows that drug-induced fatalities are the leading type of injury deaths in the U.S.; indeed, they outnumbered motor-vehicle fatalities by more than 10,000 in 2013, exactly the reverse of the situation 10 years earlier.

However, other statistics in the same report are more hopeful. The share of DEA survey respondents around the country reporting "high" illicit availability of opioids shrank to 56.7 percent in 2015 from 75.4 percent last year. The percentage of high school seniors abusing prescription drugs declined from 15 percent to 13.9 percent between 2013 and 2014.

Possibly this is related to more cautious prescribing attitudes among physicians, as reflected in the decline of narcotics disbursed by manufacturers, from the all-time high of 17.2 billion doses in 2011, to 16.2 billion in 2013. Data for the first nine months of 2014 suggest a continuation of that trend. The "pill mill" phenomenon is being brought under control, with the help of State Prescription Drug Monitoring Programs.

The grimmest statistic in the DEA report is the near-doubling in heroin overdose deaths between 2011 and 2013, from 4,397 to 8,257. This is partly an unintended consequence of the reduced illicit availability of prescription opioids, as those addicted to pills switch to cheaper heroin. The jump-starting of previously dormant heroin markets in small-city and rural America is one of the saddest offshoots of the prescription opioid flood; whether it proves temporary or permanent will depend in large part on the policies implemented in the next presidential term and beyond. The DEA's evidence of an incipient leveling off in opioid abuse provides no basis for complacency but some reason for optimism.

FROM AN EDITORIAL IN THE WASHINGTON POST