This doctrine raises more questions than it resolves. What is an "improper" appropriation? As the Arnstein test framed the issue, the original piece must sound distinct and memorable to "the ordinary lay hearer." In other words, the song cannot be confused with any subsequent songs. A 12-bar blues piece with a standard I-IV-V chord progression, for example, is so common that it's hard to imagine any song in that idiom claiming unique distinction. But what cases in which one song partially overlaps with a song with a highly complex structure? Let's face it. The odds are pretty high that any songwriter who practices his craft long enough eventually will come up with material that sounds borrowed. Though plagiarism might not be intended, such songs, if only for a few bars, could serve as the basis of a lawsuit. So who gets to sue whom and for how much? To understand the difficulty in arriving at a fair decision and settlement, consider the following scenario.

Assume that Michael Jackson and Sony/ATV Music, who jointly own most of the Lennon & McCartney catalog, sue various "imitators" of the Beatles' "Tomorrow Never Knows." After all, that 1966 classic, with its psychedelic drone and recurring flatted-7th, provided a rough archetype for countless songs, including Love & Rockets' "Yin and Yang (the Flowerpot Man)," Echo & the Bunnymen's "Lips Like Sugar" and Kasabian's "Sun Rise Light Flies." But wait a minute. That Beatles tune resembles bits of the Kinks' "See My Friends," released a year earlier. And the Kinks' Ray Davies admits to having been influenced in that instance by an Indian fishermen's chant during a band tour stop in Bombay. So the Kinks sue the Beatles, and a group of Indian fishermen in turn sue the Kinks, and everyone who is sued in turn files a countersuit.

It's an insane scenario, right? Yet a good many real-world plagiarism suits have been based on claims only somewhat less far-fetched. Bringing in experts to testify can do only so much to clear the air. Even the most knowledgeable witnesses in the end can make only an educated guess as to how a song will affect an "ordinary" lay hearer. Maybe such a listener has heard the songs in question before, but then again he's not certain. And if he has, can he match the tune with the composer/artist? And even given this level of knowledge, would that dissuade him from buying the "original" record, thus depriving its artist(s) of royalties? The difficulty in assigning to a court the role of musicologist explains why plagiarism lawsuits tend to have unsatisfying outcomes and comic undertones.

Perhaps the best-known case involved George Harrison's putative lifting of the melody of the Chiffons' 1963 hit, "He's So Fine," for his own late 1970 single, "My Sweet Lord." Early in 1971, Harrison suddenly found his royalty payments halted by court order. A U.S. District Court eventually ruled in Bright Tunes Music v. Harrisongs Music (420 F. Supp. 177 [S.D.N.Y. 1976]), that George had unintentionally copied the Chiffons' hit, but was liable for damages, though he publicly had stated his inspiration for the song was the Edwin Hawkins Singers' 1969 hit, "Oh Happy Day." The court ordered Harrison to forfeit most of the royalties from "My Sweet Lord," plus a portion of the royalties from the triple-LP on which it appeared, All Things Must Pass.

Don't think that frivolous plaintiffs' suits can't happen in foreign countries -- or that American artists can't be targets. In 2005, Belgian songwriter Salvatore Acquaviva won a judgment against Madonna, claiming that her 1998 hit, "Frozen" (co-written by Madonna and Patrick Leonard), had been lifted from his early-80s song, "Ma View Fout L'camp" ("My Life's Getting Nowhere"). The Mons-based judge declined to award damages, but did order the withdrawal of all remaining discs for sale and barred the song from Belgian TV and radio airplay. The "plagiarism" in question consisted of the song's opening four-bar theme. Welcome to justice, Walloon-style.

Even unsuccessful suits impose burdens on a defendant. In Selle v. Gibb (741 F.2d 896 [7th Cir. 1984]), the plaintiff, a Chicago-based songwriter named Ronald H. Selle, sued the Bee Gees' Maurice, Robin and Barry Gibb, alleging their 1977 hit, "How Deep Is Your Love," stole the melody of his own never-released 1975 song, "Let It End." Having seen the movie ("Saturday Night Fever") whose soundtrack contained the Bee Gees' song, he sued the band, Paramount Pictures, and Polygram Records. The Bee Gees eventually prevailed in a cross-appeal after an initial defeat. The judge ruled that the plaintiff failed to establish proof of plagiarism, but ordered each party to pay its legal bills anyway.

Such lawsuits, unfortunately, are a fact of life. Check out the files of the Columbia Law School Music Plagiarism Project for some unintentional humor as well as lessons in copyright law. But also consider the larger issue.

The state of music, and for that matter, novels, drama, cinema, painting and other art forms, would be far poorer if their creators had to live in constant fear of frivolous copyright suits. The creative process, even among the most original artists, inevitably involves a certain amount of building on others' ideas. Rendering artists liable for even fleeting, unintended similarities would stifle spontaneity, the seed of all creative work, and the commercial enterprises supporting it. This is entirely different from situations in which someone, without authorization, downloads or otherwise copies intellectual property and sells it on the black market.

The bar for plagiarism should be set higher to ward off suits in search of a quick buck. To be sure, even in a post-Arnstein environment, the lawsuit should be a final option. But courts have to display more skepticism in reviewing plaintiffs' claims.

In the meantime, forget the lawyers and crank up the radio. The Boss is back.