Fighting drug abuse is like economics: It’s all about supply and demand.

You can work with pharmaceutical manufacturers and the doctors who write prescriptions for addictive pain medication in ways to make the drugs harder to abuse and harder for addicts to get.

You soon will find what officials in Vermont recently announced. Lowering the supply of prescription drugs has just increased the use of illegal drugs, particularly heroin. The same thing has been happening in Maine, where state officials say opiate addiction is increasing even as successful steps have been employed against prescription drug abuse.

This is the danger of treating drug abuse as strictly a law enforcement problem and not treating it as what it is: a public health problem.

In addition to reducing supply, a successful drug abuse strategy also attacks demand. That means investing in treatment.

Unfortunately, that’s not the direction Maine is going. On Jan. 1, two-year caps for treatment with methadone and buprenorphine, the two most effective drugs for treating opiate addiction, go into effect. The caps will be applied retroactively, which means that some addicts will be cut off abruptly.

The state’s Office of Drug Abuse will put an effort into prevention, which is crucial to a successful campaign. Reducting supply, however, will just make the people already addicted more resourceful.

It is the wrong way to save money, and shows that the state stil isl thinking about drug abuse as primarily a law enforcement problem.

Opiate addiction is a lifelong problem, and relapses are common. Some people stay on maintenance programs far longer than two years, and are able to live productive lives as a result. Not everybody succeeds, but at least addicts commit fewer crimes when they are in treatment and don’t boost demand for black market drugs.

A supply-side approach to attacking drug abuse makes sense only if there is a strong demand-side strategy at the same time.

When the Legislature comes back to Augusta, its members should consider whether they really want to impose cuts on drug treatment at a time when addiction is on the rise.