Solicitor General of the United States

The United States Solicitor General is the fourth-highest-ranking official in the U.S. Department of Justice. 
The United States Solicitor General is the person appointed to represent the federal government of the United States before the Supreme Court of the United States. The current Solicitor General, Elizabeth Prelogar on October 28, 2021.
The Solicitor General determines the legal position that the United States will take in the Supreme Court. In addition to supervising and conducting cases in which the government is a party, the office of the Solicitor General also files "amicus curiae" briefs in cases in which the federal government has a significant interest in the legal issue. 
The office of the Solicitor General argues on behalf of the government in virtually every case in which the United States is a party, and also argues in most of the cases in which the government has filed an "amicus" brief.