Affiliates of UnitedHealth Group Inc. the nation’s largest health insurer, have taken their first shot at knocking out a class action lawsuit claiming they are illegally underpaying reimbursements for mental health services.

Lawyers at Zuckerman Spaeder and Psych-Appeal, Inc. sued United Healthcare Insurance Co. and United Behavioral Health in October claiming that the companies imposed arbitrary reimbursement penalties for certain psychotherapy services provided by psychologists and master’s-level counselors rather than doctors. Their client, an anonymous Pennsylvania woman, claimed UnitedHealth reduced the “eligible expense” of charges from her counselor by 35 percent, even though there would have been no reduction for identical services had they been provided by a physician.

In a motion to dismiss filed by UnitedHealth’s lawyers at Crowell & Moring, the company claims that the lawsuit “challenges the common sense practice that health plans reimburse health care providers with different training, experience, and licensure at different rates.”

“Contrary to plaintiff’s suggestion, it is not unlawful for [the UnitedHealthcare defendants] to pay a social worker less than a licensed physician would be paid for the same service,” the defense lawyers wrote.

UnitedHealth contends that the plaintiff does not identify a covered medical or surgical practice comparable to the reimbursement terms she challenged needed to support a claim under the Mental Health Parity and Addiction Equity Act—a 2008 law which provided additional antidiscrimination provision within the Employee Retirement Income Security Act, or ERISA.

What’s more, the Crowell lawyers argue that plaintiff failed to show a so-called “parity violation” to support her ERISA claims, and therefore her request for an injunction barring the differing reimbursement practices going forward must be denied.

The underlying lawsuit also claims that UnitedHealth violates that Section 2706 of the Affordable Care Act, which prohibits discrimination against coverage for psychologists and master’s-level counselors when they act within the scope of their state licenses. But UnitedHealth’s lawyers contend that because Section 2706 does not provide for a private right of action, the plaintiff lacks standing to sue under the statute.

Crowell’s Jennifer Romano, the Los Angeles-based co-chair of the firm’s litigation group who is among defense counsel listed on Monday’s filing, didn’t respond to a message for comment Wednesday. A UnitedHealth representative previously said the company doesn’t comment on pending litigation.

On Tuesday, U.S. District Judge Haywood Gilliam Jr., who is overseeing the case, granted a stipulated request from the parties to extend briefing deadlines in the matter. A hearing on UnitedHealth’s motion to dismiss is set for March 21, 2019 in Gilliam’s Oakland courtroom.