In a long awaited move, the Obama administration today unveiled a set of regulations that will require insurance companies to cover treatment for addiction and mental illnesses in the same way they cover physical ailments.

The announcement, made by Health and Human Services Secretary Kathleen Sebelius, is actually five years in the making. In 2008, the federal government signed the Mental Health Parity and Addiction Equity Act in an effort to bolster mental health care across the country. Delays, largely due to challenges in determining how the law would be implemented, were finally overcome earlier this year. That's when President Obama included the parity act on a list of executive actions to curb violent events like the Sandy Hook shooting.

"This final rule breaks down barriers that stand in the way of treatment."

"This final rule breaks down barriers that stand in the way of treatment and recovery services for millions of Americans," Sebelius told reporters in a speech that described the law as "the largest expansion of behavioral health benefits in a generation."

Given that an estimated 20 percent of Americans suffer from a mental illness each year, the rules could have a widespread impact. Insurance companies will need to charge co-pays and deductibles similar to what they'd levy for visits to address a physical problem. They'll also be prevented from restricting the number of mental health appointments a patient can have — much like a patient with cancer wouldn't be limited to 10 annual treatment sessions, for instance, a person with clinical depression can't be cut off after 10 therapy appointments. The rules also prevent insurers from denying coverage to patients with a history of mental illness.

Insurers have also warned the law could cause premiums to increase

Perhaps not surprisingly, insurance companies have disputed the parity law. Primarily, they've contended that psychological ailments can't be accurately compared to physical ones, and so shouldn't be governed by equal coverage principles. Insurers have also warned the law could cause premiums to increase, largely because of a surge of patients taking advantage of the coverage.

The rules will apply to Americans whose health plan includes mental health and addiction coverage, as well as anyone buying insurance under the Affordable Care Act, officials said. They won't yet impact those with Medicaid or Medicare, and employers won't be required to offer mental health benefits if they don't already.

"We look forward to a new chapter in mental health care."

Mental health advocates are celebrating the move — all while cautioning that an influx of patients seeking care threatens to overwhelm what's already an understaffed, inadequate network of clinics, programs, and practitioners. "People with mental illness have long faced discrimination in health care through unjust and often illegal barriers," said Jeffrey Lieberman, president of the American Psychiatric Association, in a statement. "We look forward to a new chapter in mental health care that delivers on the promise of the parity law."