Since the Newtown massacre, both supporters and opponents of tougher gun regulation have talked a lot about the parallel issue of inadequate monitoring of and treatment for violence-prone people with mental health problems. In the March-April issue of the Washington Monthly, one of the country’s preeminent health policy wonks, the University of Chicago’s Harold Pollack, addresses this issue comprehensively, and concludes that the single most important thing America can do to prevent violent acts by the mentally ill is pretty simple: fully implement Obamacare.

Why do so many people at risk—many of them young low-income men—fail to receive appropriate mental health services? The most important single reason is this: most are categorically ineligible for Medicaid. These men are not custodial parents. They are not veterans. They have not (yet) been diagnosed with federally recognized disabilities. Many get into trouble because they have serious drug or alcohol disorders. Since 1996, substance use disorders are no longer qualifying conditions for federal disability programs.

People often assume that an unattached adult might qualify for Medicaid if he is sufficiently poor. In fact, only a handful of states provide such coverage, even for individuals with no income at all. The homeless man who is not deemed physically or mentally disabled but who does suffer from chronic alcohol or crack dependence is typically ineligible for Medicaid. He might need substance abuse treatment or mental health care (not to mention care for any number of other health needs). If he’s locked up, the correctional service is required to provide these services. If he’s out in the community, he’s both more vulnerable and more bereft of help. He’s reliant on a patchwork of safety-net services, public hospitals, clinics, and emergency departments that’s financially stressed and disorganized under the best of circumstances, and that often allows vulnerable and occasionally dangerous people to fall through the cracks.

This will begin to change in 2014. That’s when the ACA will start providing subsidies that will eventually reach thirty-three million Americans without health insurance. An estimated sixteen million will eventually be covered by expanded Medicaid to low-income Americans with incomes below 138 percent of the federal poverty line. That number will include the hundreds of thousands of mentally ill men cycling in and out of places like Chicago’s Cook County Jail and sleeping on grates in cities from Washington, D.C., to Seattle. For the first time, nearly all of these individuals (undocumented immigrants are the big exception) will gain access to regular health care. Moreover, if the law is properly implemented, these same individuals will gain access to mental health services that can reduce their propensity to commit violent acts.

The resistance of some Republican-governed states to implementation of Obamacare’s Medicaid expansion is one threat to this progress. But there are others, notes Pollack:

We must also reverse recent punishing cuts to our mental health system. Between 2009 and 2011, states experienced a cumulative shortfall of $432 billion. Mental health agencies in almost every state have cut expenditures, even as recession increases demand for community mental health services, crisis services, and emergency department services.

The ACA helps to address some of this problem, since outpatient mental health services for “non-Medicaid low income consumers” have faced particularly deep cuts. Yet the problems go deeper, including the continued decline in the number of state psychiatric beds. As state hospitals continue to contract in the face of fiscal difficulties, psychiatric emergency rooms, nursing homes, and acute care facilities face growing burdens, seeking to serve the sickest segments of the mentally ill population, who would once have received institutional care.

It’s a challenge involving new and old policies, the complexities of the intergovernmental system, not to mention money, politics, and age-old prejudices. But, says Pollack, it’s time to begin getting this right:

It’s naive to believe that we could specifically identify someone such as Adam Lanza before he goes on a rampage, but improved policies could still prevent an unknown, maybe unknowable number of violent deaths. No one policy will dramatically reduce homicides, and the politics and administration of effective mental health policy are both daunting. But making these policies work would provide a fitting memorial to the victims of needless violence across America.

Ed Kilgore

Ed Kilgore is a political columnist for New York and managing editor at the Democratic Strategist website. He was a contributing writer at the Washington Monthly from January 2012 until November 2015, and was the principal contributor to the Political Animal blog.