The Justice Department is suing to block UnitedHealth Group’s $3.3 billion purchase of Amedisys, citing concerns the combination would hinder access to home health and hospice services in the U.S. The antitrust complaint, filed in Maryland by the Justice Department and four states’ attorneys general Tuesday, argues that a potential merger is illegal because the two companies are “such large competitors” already — and the deal would give UnitedHealth too much control in many local markets. That would mean less choice for patients looking for affordable care, the suit alleges, as well as fewer employment options for nurses seeking competitive...