Even before divers recovered the body of John F. Kennedy Jr. from the ocean waters off Martha’s Vineyard, the tchotchke hawkers had already surfaced. A figurine of 3-year-old John-John flashing his famous salute, for example, fetched $700 in an online auction. There was no shortage of those seeking to cash in on the late son of Camelot.

A flood of souvenirs and other memorabilia is inevitable every time a celebrity hits it big — in life or in death. But it’s also often illegal, according to intellectual property lawyers who represent famous clients or their estates. That’s what Mark Lee, a partner at L.A.’s Manatt, Phelps & Phillips, will argue this week before the Ninth Circuit U.S. Court of Appeals. He represents the Diana Princess of Wales Memorial Fund in a right-of-publicity dispute with Franklin Mint, which responded to Diana’s death two years ago by mass-marketing her image on everything from commemorative plates to porcelain dolls, along with selling replicas of her royal jewels.