On Wednesday, the Justice Department filed an antitrust lawsuit challenge insurance broker Aon PPLC’s proposed $35 billion acquisition of rival Willis Towers Watson PLC, alleging the tie-up would lead to higher prices and reduced innovation for US businesses, employers, and unions that rely on their services.The department, which filed the lawsuit in a Washington federal court, stated that the merger would get rid of competition in several different US product markets, including brokering services for property, casualty, and liability insurance, as well as health benefits for large corporate clients.The lawsuit, coming after an investigation of more than a year, marks the Justice Department’s first major antitrust action during the Biden administration, which is poised to take an aggressive positioning against mergers in industries that already have few competitors.President Biden’s complete antitrust-enforcement team is still taking shape, but indications so far are that he wants his nominees to challenge potentially anti-competitive business practices by powerful companies and hold the line against the formation of new mega-firms with an unchecked ability to impose prices and terms that affect consumers.