WASHINGTON, D.C.—The health insurance companies Aetna and Humana have been blocked in their attempt to merge their businesses by a federal judge, who issued a 158-page opinion preempting the deal earlier this week.

The two companies made their case around the belief that the merger of the two businesses would create a more efficient operation, which would allow the anticipated savings to be passed on to consumers.

As of late Tuesday afternoon, Aetna and Humana were reported to be considering all available options to the court’s ruling.

In blocking the proposed deal Judge John D. Bates of the U.S. District Court for the District of Columbia said the court “mostly agrees” with the Justice Department’s position that the proposed deal reduces competition in some areas of health insurance.

In July, the Justice Department moved to block the proposed $37 billion merger of the two companies, as VMail reported, citing its view that the combination of the two companies would reduce competition in the Medicare Advantage market.

“The Court is unpersuaded that the efficiencies generated by the merger will be sufficient to mitigate the anticompetitive effects for consumers in the challenged markets,” U.S. District Judge John D. Bates wrote in his 158-page opinion, according to news reports about the court decision.

A separate $48 billion proposed mega-merger of large health insurers, Anthem and Cigna, is awaiting a decision by another federal judge on their proposed deal. The deals were both challenged by the Obama administration.