A federal judge Wednesday blocked Anthem’s proposed merger with Cigna -- a move that appears to shut the door on what could have created the largest health insurance conglomerate in American history. The judge in the case said the merger -- which could have affected up to 53 million consumers -- would unduly reduce competition in the healthcare economy, according to Bloomberg.

"The antitrust laws are designed to protect competition, and the claimed efficiencies do not arise out of, or facilitate, competition," Judge Amy Berman Jackson wrote in the ruling.

The blocked deal was worth more than $50 billion.

Read: Secret Records And Lack Of Hearings Raise Concerns In Merger Review

The American Medical Association called the  ruling "an important victory for consumers."  

"The AMA agrees with Judge Jackson’s conclusion that Anthem’s strategy of gaining size to strong-arm physicians would not have benefited consumers," said the statement released by AMA president Andrew W. Gurman. "Instead, it would diminish prospects for innovation in health care delivery and payment."

Less than a year ago, the merger proposal was flying under the radar, generating little controversy or opposition. In June, however, an International Business Times investigation detailed how the Connecticut state regulator leading the national antitrust review of the merger had personal, financial and familial ties to Cigna.

That regulator, Connecticut Insurance Commissioner Katharine Wade, was appointed by Connecticut Gov. Dan Malloy -- as Malloy’s Democratic political groups received hundreds of thousands of dollars of campaign contributions from Anthem and Cigna. Wade, a former Cigna lobbyist, was leading the national regulatory review of the merger because Cigna is domiciled in Connecticut.

Cigna and Anthem lobbied extensively during the merger proceedings. Government documents obtained by IBT revealed that even while Malloy publicly pledged to remain impartial, his administration explicitly offered to help Cigna with the merger. As Cigna and Anthem campaign cash poured into the governor's political apparatus, Malloy also quietly signed legislation designed to help Wade keep insurance industry information concealed from the public. 

Read: What Malloy's Insurance Commissioner Told Ethics Officials 

The disclosures prompted bipartisan calls for recusal and a state ethics probe, while also drawing national attention to the deal’s potential healthcare implications for millions of Americans. The companies argued that the merger would generate cost savings that could be passed onto consumers. Critics charged that the merger could raise prices and limit medical options for consumers -- and that the regulatory review had been tainted by conflicts of interest.

Amid the controversy in late June,  Connecticut’s U.S. Senator, Richard Blumenthal, spearheaded federal lawmakers’ effort to pressure the Obama administration to try to block the merger. Soon after, the administration did exactly that, filing a lawsuit against the merger proposal and against a separate merger proposal by Aetna and Humana. Commissioner Wade ultimately recused herself from the proceedings.

Both mergers have now been blocked. It is not yet clear whether the companies will appeal the rulings.