For more than a dozen years, advocates have fought to lift restrictions on mental health coverage in insurance policies.

On Friday, they won an enormous victory when Congress passed the Paul Wellstone and Pete Domenici Mental Health Parity & Addiction Equity Act of 2008.

The law doesn’t require health insurers to cover mental health care. But if they do, they’ll have to treat psychological and addictive disorders just as they do other medical conditions.

Put another way, insurers will no longer be able to limit the number of visits or charge higher deductibles and co-payments for mental health and substance abuse services.

“If you have insurance, then your mental health care must be equal to the benefits you get for any other disease,” said Sen. Pete Domenici (R-N.M.), quoted in a Reuters article. His daughter has schizophrenia.

President Bush signed the bill into law after it was tacked onto the $700 billion financial bailout bill the House of Representatives passed 263-171 on Friday.