SECTION I OF THE SHERMAN ACT, DESPITE ITS BREVITY, FUNCTIONS AS TWO STATUTES: A CRIMINAL STATUTE DEALING WITH HARDCORE VIOLATIONS -- PRICE FIXING, MARKET ALLOCATION, AND SIMILAR CONDUCT; AND A CIVIL STATUTE OF CONSIDERABLE BREADTH AND FLEXIBILITY. OVER THE YEARS, THE SHERMAN ACT HAS BEEN VIEWED ALTERNATIVELY AS PRIMARILY A CIVIL OR A CRIMINAL STATUTE. AS OF 1977, THE ANTITRUST DIVISION WAS DEVOTING A LARGER SHARE OF ITS RESOURCES TO CRIMINAL ENFORCEMENT THAN IT HAD AT ANY TIME SINCE THE YEARS BETWEEN 1938 AND 1943. DURING HIS TENURE FROM AUGUST 1976 TO MAY 1977 AS ASSISTANT ATTORNEY GENERAL IN CHARGE OF THE ANTITRUST DIVISION, THE AUTHOR, BELIEVING THAT CRIMINAL SANCTIONS BEST DETER ANTITRUST CRIMES, OPTED FOR CRIMINAL PROSECUTIONS IN PRICE-FIXING AND MARKET-ALLOCATION CASES, ABSENT ANY OF THE FOLLOWING MITIGATING FACTORS: CONFUSION OF THE LAW; TRULY NOVEL ISSUES OF LAW OR FACT; CONFUSION CAUSED BY PAST PROSECUTORIAL DECISIONS; OR CLEAR EVIDENCE THAT THE DEFENDANTS DID NOT APPRECIATE THE CONSEQUENCES OF THEIR ACTIONS. ALTHOUGH ARTICULATION AND CONSISTENT APPLICATION OF PRINCIPLES OF DECIDING THE FORM OF PROCEEDING GIVE PARTIES SOME NOTICE OF THE STANDARDS TO WHICH THEIR CONDUCT WILL BE HELD, THE CRIMINAL-VERSUS-CIVIL DECISION IN CLOSE CASES ULTIMATELY REQUIRES THE JUDGMENT OF THE ASSISTANT ATTORNEY GENERAL. (AUTHOR ABSTRACT MODIFIED)