That was the riddle before U.S. District Judge Harry L. Hupp in Los Angeles on Monday. It was a legal puzzle about the graying of rock and roll - whether a middle-aged musician who helped found a legendary band can continue to link himself professionally to the glorious days of his youth.

For trademark reasons, Judge Hupp decided that original Beach Boy singer and guitarist Al Jardine, 57, is not a Beach Boy. Noting that he "had never seen anything quite like" the trademark infringement case involving Jardine, Hupp concluded that Jardine may not trumpet his nearly four decades as a member of a group that once rivaled the Beatles.

Specifically, Hupp determined that Jardine may not use the phrase Beach Boy on marquees and in advertising because such use infringes on the rights of Brother Records, the Beach Boys' holding corporation. Moreover, Jardine may not use the plural term Beach Boys to promote his current act, Alan Jardine's Beach Boys Family and Friends, Hupp said in granting a preliminary injunction sought by Brother Records. For the time being, Hupp left up in the air the subsidiary question of whether Jardine may refer to himself as a Beach Boy in biographical information, press interviews and other non-promotional material. Brother Records v. Jardine, 99-3829.

"He's using the name Beach Boy or Beach Boys in the title of his band," Hupp said, explaining that use of the beach words was "likely" to lead to confusion in the public mind about who was whom.

The irony is that Jardine, as one of the original members of the group founded in 1961 that had hits such as "Surfin' Safari" and "Good Vibrations," owns a 25-percent stake in Brother Records. According to statements in court, Jardine lost a bid to use the Beach Boys name to Mike Love, another 25-percenter in Brother Records and the group's original lead singer. Love currently has the right to use the Beach Boys name on tour.

Apparently, Love and the two other shareholders in Brother Records outvoted Jardine on the use of the star-crossed band's name. These other shareholders are the administrator of the estate of original Beach Boy Carl Wilson, who died of cancer in 1998, and the guardian of original Beach Boy Brian Wilson, whose psychological problems have been widely reported. A third Wilson brother, Dennis, drowned in Marina del Rey in 1983.

Hupp's decision pleased Brother Records attorney Edwin F. McPherson of McPherson & Kalmansohn, who thought Jardine should be satisfied with his own, unadorned good name and whatever fame may go with it. "Mr. Jardine's name is Al Jardine. It is not Beach Boy Al Jardine," McPherson told the judge. Jardine's attorney, Vincent H. Chieffo of Gipson Hoffman & Pancione, begged to differ as he sought to change Hupp's mind.

He argued that Jardine's identity as a musician is linked inextricably to the Beach Boys. "He has worked for 40 years in one band called the Beach Boys," Chieffo said, declaring that his client is "being unfairly hampered in his ability to compete." Although Chieffo didn't mention it, the new year may be a boom one for the surviving Beach Boys. ABC is set to broadcast a four-hour miniseries called "The Beach Boys: An American Family," and a volume of the group's greatest hits is to be released next month.

Hupp didn't disagree with Chieffo that Jardine's earning capacity will take a hit from the injunction. But he pointed out that Brother Records holds the rights in the Beach Boy[s] name. "You've got 75 percent of the stock against you," he told Chieffo.

Among other things, Hupp discounted Chieffo's argument that Jardine's use of the Beach Boy name amounted to "nominative fair use." The Beach Boys trademark has transferred to Brother Records, Hupp wrote in his ruling. "Thus, the possibility of confusion exists, and in any event Jardine would be using the name to solicit business with another's trademark."

In a small victory for Jardine, Hupp said Brother Records must post a $250,000 bond to cover Jardine's lost income should a jury eventually find in his favor.

After the hearing, I asked Chieffo if he expected the case to go to trial. "Yes," he answered, noting that Jardine has filed a breach of contract cross-complaint against Brother Records. Meanwhile, he said, he had to track down his client, who lives in Big Sur, and give him the bad news.