United States Attorney General
The United States Attorney General is the chief law enforcement officer of the United States Government. The Attorney General is in charge of the United States Department of Justice. The Attorney General is a Cabinet-level post, appointed by the President of the United States and confirmed by the United States Senate. As outlined by the Presidential Succession Act of 1947, the Attorney General is seventh in line of succession. 
Current Attorney General
Biography of Eric Holder
Attorney General Holder received an undergraduate degree in American History from Columbia College in 1973 and a J.D. from Columbia Law School in 1976. After receiving his law degree, Holder clerked for the NAACP Legal Defense Fund and the Criminal Division at the Department of Justice. He served as an attorney with the Public Integrity Section of the DOJ and later was a partner in private practice with the firm Covington & Burling LLP. 
The Attorney General is appointed by the President of the United States and confirmed by the United States Senate. He or she serves at the pleasure of the President and can be removed by the President at any time. 
History of the office
The position of Attorney General was established by the Judiciary Act of 1789, which called for an individual to "prosecute and conduct all suits in the Supreme Court in which the United States shall be concerned..."  On July 1, 1870, the modern Department of Justice was created with the Act to Establish the Department of Justice. The department was responsible for all criminal and civil suits affecting the United States, in addition to federal law enforcement. The Office of the Solicitor General was also created at this time. 
Responsibilities of the Department of Justice
The members of the Department of Justice represent the United States in legal matters generally and offer advice and opinions to the President and to the heads of the executive departments of the Government when so requested. The Attorney General appears in person to represent the Government before the Supreme Court of the United States in cases of exceptional importance. Under most circumstances the United States Solicitor General argues before the Supreme Court on the government's behalf.
History of the office
The first Attorney General of the United States was Edmund Jennings Randolph, who served in the position from 1789 to 1794. Below is a table of all other United States Attorneys General, in addition to their years of service. (External links will direct you to official biographies from the United States Department of Justice website.)
The average term in office a United States Attorney General, prior to the current officeholder, is 2.67 years.