A federal trial judge has certified a class action filed againstBlue Shield of California and Magellan Health Inc. forsystematically restricting insurance coverage for mental health andsubstance abuse treatment.

Certification means the case can proceed; if it weren'tcertified, it would be dismissed.

In her June 15 order, U.S. District Judge Lucy Koh of theNorthern District of California granted class certification forEmployment Retirement Income Security Act group plan members whoseclaims for residential and intensive outpatient mental health andsubstance abuse treatment were rejected by insurer Blue Shield andhealth care provider Magellan based on the companies’ “medicalnecessity criteria guidelines” from Jan. 1, 2012, to thepresent.

It’s the latest victory in a niche market dominated by a handfulof health care plaintiffs lawyers who go after insurers fordisparate treatment of behavioral health issues in violation ofERISA and depending on the case, the Mental Health Parity andAddiction Equity Act of 2008.

Related: Humana calls FTC subpoena 'fishingexpedition'

This most recent suit alleges that the criteria Blue Shield andMagellan used to restrict coverage for this type of care “areinconsistent with the terms of the relevant insurance plans andgenerally accepted professional standards in the mental health andsubstance abuse disorder treatment community.”

Magellan declined to comment on the case. A Blue Shieldspokesman declined to comment on the specifics of the pendinglitigation but said that, “We disagree with the allegations in thelawsuit and the court’s certification of a class in this case. Weintend to continue to defend the case vigorously.”

Another class action that was certified by a federal judge inConnecticut last month alleges Aetna Inc. systematically deniedinsurance coverage for transcranial magnetic stimulation to treatsevere depression.

Representing the plaintiffs in both cases are Zuckerman Spaederand Psych-Appeal Inc., a West Hollywood, California, law firmdevoted to mental health insurance law.

The two firms have successfully collaborated on around six casesof this kind since they teamed up a few years ago. LeClairRyan isco-counsel in the Aetna case, and Grant & Eisenhofer isco-counsel in the Blue Shield and Magellan matter.

“The cases have been successful because they speak to systematicabuses that are relatable, and the remedies we are seeking are justintrinsically fair,” said Meiram Bendat, president of Psych-Appeal,who is both a psychotherapist and a lawyer. “They’re requiring theinsurers to essentially conform their practices to the properstandard of care.”

Zuckerman partner D. Brian Hufford agreed that much of thesuccess is due, at least in the California case, to what theplaintiffs are asking for.

“We’re not directly saying, ‘You’ve got to reward benefits,’” heexplained. “We’re saying: ‘You used the wrong standard or appliedthe wrong decision and, therefore, you need to go back and use theproper guidelines.’ … This area is complex, but we’ve been able tocome up with, after years of development, strong legaltheories.”

So where do those years of development start?

For Hufford, it began in the 1990s with a personal matter — ason who had a highly unusual skin condition that was difficult todiagnose.

An interest in health care law that stemmed from that experienceevolved into a specialty many years later, when Hufford, then atPomerantz Grossman Hufford Dahlstrom & Gross, negotiated a $350million settlement with UnitedHealth Group Inc. for misusing anIngenix database to set “usual, customary and reasonable” rates forout-of-network health services.

The majority of Hufford’s health care work now deals withbehavioral health, he said.

Bendat’s story also began with a child. Or lots of them. Afterrepresenting children and families in the Los Angeles child welfaresystem and treating patients, Bendat founded Psych-Appeal in 2011.And when he went looking for a health care attorney with classaction success to work with him on mental health insurance issues,Hufford’s reputation was well known.

In their first big case together, the U.S. Court of Appeals forthe Second Circuit in 2015 held that third-party benefitsadministrators can be sued under ERISA for violating the ParityAct’s requirement of equal coverage for mental health treatment.Zuckerman partner Jason Cowart, Hufford’s co-counsel in thesecases, called it a “watershed case” at the time.

And there’s much more work to be done to advocate for parity inbehavioral health benefits, Bendat said.

“To date, there’s been very little enforcement of both theparity and mental health access protection in large part due to alack of prioritization and sophistication on the part ofregulators,” he said. “But we have been able to detect and unravelthe systemic abuses that have haunted and plagued the industry forso long.”