Conservatively speaking, the U.S. Code contains at least 3,500 offenses which carry criminal penalties. More realistically, the number exceeds 4,000. (p. 11) [T]he count of 600+ [newly legislated] crimes in the seven-year period from 1997 demonstrates the estimate of over 4,000 crimes today. . . [O]ne fairly glaring trend did emerge which deserves mention. During the seven-year period of this Report from 1997, 24 of the 67 sections and subsections were created in the environmental area. That is over 35% of the total number of sections and subsections created by Congress during that period. (p. 15)
Federal prosecutors have certain favorites, notably mail and wire fraud statutes, which they use even when other statutes might be more applicable. That, of course, does not mean that the addition of little-used crimes is unimportant. The federal government is supposedly a government of limited powers and, therefore, limited jurisdiction. Every new crime expands the jurisdiction of federal law enforcement and federal courts. Regardless of whether a statute is used to indict, it is available to establish the legal basis upon which to show probable cause that a crime has been committed and, therefore, to authorize a search and seizure. The availability of more crimes also affords the prosecutor more discretion and, therefore, greater leverage against defendants. Increasing the number and variety of charges tends to dissuade defendants from fighting the charges, because (s)he usually can be “clipped” for something.
Moreover, the expansion of federal criminal law continues to occur even without new legislation. Federal prosecutors regularly stretch their theories of existing statutes. Thus, in the Martha Stewart case the prosecutors developed a “novel,” indeed ludicrous, theory that Ms. Stewart committed fraud by proclaiming her innocence of the charges. Ultimately, the trial judge rightly threw out the fraud charge. Often, though, federal courts cooperate with prosecutors and happily make new law retroactively. What (then) Professor and (later federal Judge) John Noonan wrote in 1984 about bribery and public corruption continues to be generally true, namely that federal prosecutors and federal judges have been effectively creating a common law of crimes through expansive interpretations. (p. 16-17).
Regardless of what a statute says, 1) a crime that appears not to have a mens rea may be interpreted by courts to have one; 2) a crime that appears to have a mens rea may have the mens rea diluted as applied in prosecution and as interpreted by courts. The problem of mens rea in federal criminal law is well summarized by a leading casebook, as follows:
Federal statutes, for example, provide for more than 100 types of mens rea. Even those terms most frequently used in federal legislation–“knowing” and “willful”– do not have one invariable meaning. Particularly with respect to judicial interpretation of the term “willful,” the precise requirements of these terms depend to some extent on the statutory context in which they are employed. Another layer of difficulty is attributable to the fact that Congress may impose one mens rea requirement upon certain elements of the offense and a different level of mens rea, or no mens rea at all, with respect to other elements. (p. 18)Whereas the Court in [Schick v. United States, 195 U.S. 65 (1904)], spoke of both the nature of the offense and the length of the punishment, the trend for some time in criminal law has been to consider only the length of the possible punishment. Unfortunately, potential sentences continue to rise without much, if any, consideration of moral culpability. Without that distinction, physical and financial harms – which are the focus of tort law – are too easily labeled “crimes.” (p. 22)