Mens sana in corpore sano, goes an old Latin saying. A sound mind is a sound body. It’s an ancient principle, but one that remains a modern challenge to fulfill. The Mental Health Parity Act of 2008 aimed at ensuring that health insurance companies would treat mental health on a par with physical wellness, for instance, but seven years later, a growing body of evidence indicates that the law has yet to level out longstanding disparities between insurers’ coverage of physical ailments and mental ones.

Health insurance companies still use myriad ways to block or deter patients from obtaining drugs, counseling and other mental health treatment they need, a report published Monday by Kaiser Health News showed. As insurers continue these practices, the U.S. government has done little to crack down on them and ensure that the provisions and spirit of the 2008 law are being followed.

The law, known as the Paul Wellstone and Pete Domenici Mental Health Parity and Addiction Equity Act of 2008, aimed to stop health insurance companies from imposing stricter limits on benefits for mental health or substance use care than for medical or surgical care. In 2010, the Affordable Care Act expanded the law so that parity applied not just to group health plans but to individual ones as well.

Before the 2008 law, health insurance companies could discriminate against patients with histories of mental illness, force them to pay more for treatment or limit numbers of visits, for instance, even if the insurer would not impose such restrictions on a patient with a disease like cancer, the New York Times has reported. An earlier law, from 1996, had already tried to ban insurers from setting lower ceilings on spending for mental health care than for other kinds of treatment, but they nevertheless managed to skirt the law by curbing access to treatment in other ways, such as by limiting visits to outpatient clinics. Now, mental health advocates fear that the same is happening with the 2008 law.

Insurers have been more stringent about approving or reimbursing patients for mental health care, conducted more reviews of such care or imposed harsher standards of medical necessity, as a handful of lawsuits claim. These tactics, some of which violate the 2008 law, continue to block access to mental health care for the estimated 43.7 million adults in the United States who have had any mental illness, or 18.6 percent of all adults.

Patients seeking treatment for mental illness or substance use face “serious problems in finding mental health providers in health insurance plan networks; high rates of denials of authorization for mental health and substance use care by insurers; [and] barriers to accessing psychiatric medications in health plans,” a report published in April by the National Alliance on Mental Illness, noted.

High out-of-pocket costs for prescription drugs as well as high co-pays and deductibles also prevented or deterred patients from accessing the mental health care they needed, the report found.

Some insurance plans that deploy these tactics violate the 2008 law, a study by the Johns Hopkins Bloomberg School of Public Health showed. Critics allege that the Obama administration has been lax in enforcing the law because it is trying to avoid angering insurance companies, whose support was critical for the passage of the 2010 Affordable Care Act.

But insurers contend that covering mental and physical health equitably is difficult because of the differences in the very nature of these illnesses. “A treatment plan for diabetes or a chronic heart disease is very different from a treatment plan for a patient that’s seeking care for depression or another mental illness,” Clare Krusing, a spokeswoman for the trade group America’s Health Insurance Plans, told Kaiser Health News. “It’s not a math formula.”

On paper, the law appears to help close gaps in mental health treatment, but in practice, the improvements have been incremental. “While progress is being made in law, we have a long way to go to achieve true parity in mental health and substance use care,” the report by the National Alliance on Mental Illness concluded.