What follows is an opinion from a United States Court of Appeals.
Your task is to identify the issue in the case, that is, the social and/or political context of the litigation in which more purely legal issues are argued. Put somewhat differently, this field identifies the nature of the conflict between the litigants. The focus here is on the subject matter of the controversy rather than its legal basis.
Your task is to determine the specific issue in the case within the broad category of "criminal - federal offense".

Opinion:
Vincent W. ECKEL, Appellant, v. David L. LADD, Commissioner of Patents, Appellee.
No. 19105.
United States Court of Appeals District of Columbia Circuit.
June 3, 1965.
Petition for Rehearing Denied June 28, 1965.
Certiorari Denied Nov. 8, 1965.
See 86 S.Ct. 243.
Mr. William Douglas Sellers, Pasadena, Cal., with whom Messrs. George A. Brace, Pasadena, Cal., and Munson H. Lane, Washington, D. C., were on the brief, for appellant.
Mr. S. William Cochran, Atty., U. S. Patent Office, with whom Mr. Clarence W. Moore, Sol., U. S. Patent Office, was on the brief, for appellee.
Before Prettyman, Senior Circuit Judge, and Wright and Tamm, Circuit Judges.
ORDER
PER CURIAM.
This cause came on to be heard on the record on appeal from the United States District Court for the District of Columbia, and was argued by counsel.
This court being in general agreement with the opinion filed herein by the District Court, Eckel v. Ladd, D.D.C., 233 F.Supp. 879 (1964); 1438(1).
It is ordered that the judgment of the District Court be, and it is hereby, affirmed. See Zenith Radio Corporation v. Ladd, 114 U.S.App.D.C. 54, 57, 310 F.2d 859, 862 (1962).

Question: What is the specific issue in the case within the general category of "criminal - federal offense"?

Choices:
murder
rape
arson
aggravated assault
robbery
burglary
auto theft
larceny (over $50)
other violent crimes
narcotics
alcohol related crimes, prohibition
tax fraud
firearm violations
morals charges (e.g., gambling, prostitution, obscenity)
criminal violations of government regulations of business
other white collar crime (involving no force or threat of force; e.g., embezzlement, computer fraud,bribery)
other crimes
federal offense, but specific crime not ascertained

Answer: 4