Investigation Enhancement Act of 2001 - Amends the Federal judicial code to authorize a Government attorney, for the purpose of enforcing Federal law, to provide legal advice, authorization, concurrence, direction or supervision on conducting undercover activities, and to authorize any attorney employed as an investigator or other law enforcement agent by the Department of Justice who is not authorized to represent the United States in criminal or civil law enforcement litigation or to supervise such proceedings to participate in such activities, even though such activities may require the use of deceit or misrepresentation, where such activities are consistent with Federal law.