The Hell's Angels are accused of violating the Racketeering Influenced and Corrupt Organizations Act (RICO), which was adopted nine years ago primarily to get at mobsters who had infiltrated legitimate business and labor unions. Its use has been expanded since then -- RICO was used, for example, in the trial of former Maryland Gov. Marvin Mandel.

The law is broad, controversial and believed by some to be vaguely worded, but in essence what it does is to set stiff penalties for anyone found guilty of a "pattern of racketeering" in an enterprise that affects interstate or foreign commerce. "Pattern of racketeering" means the person has committed at least two acts of racketeering -- the list includes robbery, murder, gambling and white slavery, among many other crimes -- during a period of time that can go back 10 years or more.

To prove that pattern for each defendant, the law allows prosecutors to bring up crimes already litigated -- even if the defendant has already served time for those crimes. (Barger, for example, complains, "I've never been arrested before for things I've already been in prison for.") And it lets prosecutors introduce criminal charges that would otherwise be beyond prosecution because the statute of limitations -- five years, in this case -- has run out.

To convict each defendant under the RICO charges, here is some of what prosecutors will have to prove to the Hell's Angels jury:

that the defendant commited, or conspired to commit, two acts of racketeering during the time stipulated by the law.

That the Hell's Angels Motorcycle Club was an "enterprise," under RICOs definition of the term, and that conspiring to racketeer or racketeering -- making drugs, selling drugs, and so on -- was carried out in connection with the club.

That the defendant joined the Hell's Angels or was associated with the club, and joined or conspired to join the criminal enterprise through that membership or association.