What follows is an opinion from a United States Court of Appeals.
Intervenors who participated as parties at the courts of appeals should be counted as either appellants or respondents when it can be determined whose position they supported. For example, if there were two plaintiffs who lost in district court, appealed, and were joined by four intervenors who also asked the court of appeals to reverse the district court, the number of appellants should be coded as six.
When coding the detailed nature of participants, use your personal knowledge about the participants, if you are completely confident of the accuracy of your knowledge, even if the specific information is not in the opinion. For example, if "IBM" is listed as the appellant it could be classified as "clearly national or international in scope" even if the opinion did not indicate the scope of the business. 

Your task concerns the first listed appellant. The nature of this litigant falls into the category "federal government (including DC)", specifically "other, not listed, not able to classify". Your task is to determine which specific federal government agency best describes this litigant.

Opinion:
UNITED STATES of America, Appellant, v. Errol ZEIGER.
No. 72-2065.
United States Court of Appeals, District of Columbia Circuit.
Nov. 9, 1972.
Before McGOWAN, MacKINNON and ROBB, Circuit Judges.
ORDER
PER CURIAM.
This cause came on for consideration of an appeal under 23 D.C.Code § 104(d) from an order of the District Court, 350 F.Supp. 685, dated November 7, 1972, which admitted proffered polygraph testimony, and the Court heard argument of counsel.
On consideration of the foregoing, and of the record on appeal herein, it is
Ordered by the Court that the order of the District Court appealed from in this cause is hereby reversed and this case is remanded to the District Court for further proceedings.

Question: This question concerns the first listed appellant. The nature of this litigant falls into the category "federal government (including DC)", specifically "other, not listed, not able to classify". Which specific federal government agency best describes this litigant?

Choices:
United States - in corporate capacity (i.e., as representative of "the people") - in criminal cases
United States - in corporate capacity - civil cases
special wartime agency
Other unlisted federal agency (includes the President of the US)
Unclear or nature not ascertainable

Answer: 2