On Sunday's "Last Week Tonight," host John Oliver addressed the issue of mental health in the U.S., a subject that politicians generally avoid — except in the wake of a mass shooting.

Instead of discussing the country's relatively loose gun laws as compared to other advanced nations, at least three Republican presidential candidates—Donald Trump, Ben Carson, and Mike Huckabee—have pivoted the conversation toward mental health following the Oregon shooting, and Oliver argues that it's a troubling trend.

"It seems there is nothing like a mass shooting to suddenly spark political interest in mental health," Oliver said. But though it is certainly important to have a national debate regarding the effectiveness of America's mental health system, the comedian added that talking about it directly after a mass shooting is probably not the best approach to the issue.

"The aftermath of a mass shooting might actually be the worst time to talk about mental health, because for the record, the vast majority of mentally ill people are nonviolent, and the vast majority of gun violence is committed by non-mentally ill people," Oliver said. "In fact, mentally ill people are far more likely to be the victims of violence rather than the perpetrators, so the fact that we tend to only discuss mental health in a mass shooting context is deeply misleading."

Oliver cited recent reports published in the American Journal of Public Health and the Annals of Epidemiology to demonstrate how less than five percent of the last 120,000 gun-related killings have been carried out by people who were mentally ill, and how the majority of mental ill people are nonviolent.

Even if mental illness isn't quite as closely related to the issue of mass shootings in the U.S. as some politicians seem to think, the least that could be done following these tragedies is actually work to resolve some of the very real concerns our country faces in terms of mental health services.

"If we're going to constantly use mentally ill people to dodge conversations about gun control, then the very least we owe them is a fucking plan," he said.