The U.S. Justice Department and four states sued Tuesday to block UnitedHealth Group’s proposed $3.3 billion acquisition of Amedisys, a Louisiana-based home health company that would further United’s push into the home care and hospice markets.

The complaint marks the second time in less than three years that DOJ has tried to stop Minnesota-based UnitedHealth from completing deals to bolster its fast-growing Optum division for health care services, which complement the company’s legacy health insurance business. The government unsuccessfully sued to block Optum’s acquisition of Change Healthcare in 2022.

In the new case, the government alleges the acquisition of Amedisys would harm competition because UnitedHealth previously completed a$5.4 billion acquisition of LHC Group, another home care and hospice company based in Louisiana.

“We are challenging this merger because home health and hospice patients and their families experiencing some of the most difficult moments of their lives deserve affordable, high quality care options,” Attorney General Merrick B. Garland said in a news release Tuesday. “The Justice Department will not hesitate to check unlawful consolidation and monopolization in the health care market that threatens to harm vulnerable patients, their families and health care workers.”

UnitedHealth Group runs UnitedHealthcare, which is the nation’s largest health insurer, as well as Optum, which manages pharmacy benefits, outpatient medical centers, medical billing and health care data analytics for millions of patients across the country.

In a statement UnitedHealth Group said the “combination with Optum would be pro-competitive and further innovation, leading to improved patient outcomes and greater access to quality care. We will vigorously defend against the DOJ’s overreaching interpretation of the antitrust laws.”

DOJ filed the lawsuit in U.S. District Court in Maryland, with four states as co-plaintiffs: Illinois, Maryland, New Jersey and New York.

In February 2022, the Justice Department filed a civil lawsuit to block UnitedHealth’s $13 billion acquisition of Tennessee-based Change Healthcare, a bigger deal that the federal government said could potentially harm millions of Americans by lowering the quality of health insurance while making coverage more costly.

The judge in that case ruled that DOJ didn’t make its case that the company would either misuse Change Healthcare’s data to promote its own health insurance business or to raise rivals’ costs and limit innovation.

Earlier this year, the Wall Street Journal cited unnamed sources saying DOJ had opened an antitrust investigation related to UnitedHealth’s acquisition of medical groups across the country.