One of the leading Republican candidates for president tells heartbreaking stories of violence committed by a few Mexican immigrants as evidence that they are rapists, murderers, criminals and drug dealers. He depends on outrage and fear to gain support for building a 2,000-mile fence and detaining and deporting millions of individuals.

A similar tactic is being used to influence national policies about people with serious mental illnesses in the wake of well-publicized mass murders. The intention is to cause fear by linking violence and mental illness, and then blaming the illnesses and the mental health system for the problems. The proposed solutions? A return to asylums; more involuntary outpatient commitment; attacks on a federal agency that has spearheaded advances in mental health policies and services; and challenges to the nation's emphasis on protecting the rights and freedoms of all citizens.

This strategy perpetuates inaccurate beliefs, is ineffective and harmful to those who are targeted, and will cost billions of dollars if implemented.

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Mass murders committed by people with mental illnesses are exceedingly rare. A recent study published in the American Journal of Public Health demonstrated that people with mental illnesses are no more likely to kill others with a gun than the general population. Authors of a previous article in the same prestigious journal concluded that solutions to gun violence that target people with mental illnesses are unlikely to have an effect.

The percentage of people with serious mental illnesses is virtually identical around the world. Yet only in the United States are violence and crime seriously discussed as being related to those with mental illnesses. And the mental health system in the United States, while not close to being perfect, is arguably among the most advanced in the world, undermining arguments that it is at fault.

In addition to being misleading, playing the "violence and crime card" maintains, and possibly exacerbates, ingrained prejudices and discrimination toward people with mental illnesses. Ironically, these narratives more likely drive people away from needed services out of fear of being labeled "crazy" and "violent." In addition, individuals with serious mental illnesses report having less meaning in their lives and being lonely, which contributes to the horrifyingly high suicide rate among this population that is not talked about enough.

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The proposed solutions are equally problematic. Mental institutions are anything but the idyllic healing settings that some supposed experts have claimed. And like building a 2,000-mile border fence or rounding up millions of people already in the United States, they would come at a great cost without the desired impact.

Commitment laws already balance the rights of the individual with the necessities of protecting society and these individuals from harming themselves. Regrettably, these laws do not prevent all harms from occurring, but they do prevent the damage that invariably comes from casting an overly broad net.

Finally, attacks on the Substance Abuse and Mental Health Services Administration also seem strangely off course. This federal agency has dutifully carried out the wishes of legislators who passed the Americans with Disabilities Act, the Supreme Court that upheld the ADA, and President George H.W. Bush, who launched the New Freedom Initiative to enhance the lives of American citizens with mental illnesses and other disabilities.

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SAMHSA has clearly served people with serious mental illnesses, including those who are homeless, are suicidal, have limited access to health care, or lack the resources to live successfully in the community. The agency's efforts have produced service delivery concepts and approaches that have been adopted by every state and municipality in the United States - and, in some cases, by countries around the world. The elimination or curtailment of SAMHSA would be a major blow to progressive mental health policies in the United States, and attacks on the group's protection and advocacy efforts fly in the face of liberty and human rights.

While it's among the best systems in the world, we can all agree that mental health services in the United States are not perfect. Millions of Americans with the most serious mental illnesses are not living lives in the community like everyone else.

These individuals do not have opportunities to work, go to school, parent, and love and be loved, all of which promote mental health and wellness.

These serious public health issues are only exacerbated by the violence-and-crime narrative, which in turn only inflames prejudice and discrimination.

Mark Salzer is a professor and the chair of the department of rehabilitation sciences at Temple University. He wrote this for The Philadelphia Inquirer.