The Obama administration issued a final rule on Wednesday defining “essential health benefits” that must be offered by most health insurance plans next year, and it said that 32 million people would gain access to coverage of mental health care as a result. The federal rule requires insurers to cover treatment of mental illnesses, behavioral disorders, drug addiction and alcohol abuse, and other conditions. Kathleen Sebelius, the secretary of health and human services, said that in addition to the millions who would gain access to mental health care, 30 million people who already have some mental health coverage will see...