It is entirely possible that Crichton never got around to changing his will—which was last amended in October 2007—to address his second child. The law in California and many other states provides for this circumstance, leaving a way for a child born after the signing of a will to claim his or her inheritance as if the parent had died without an estate plan.

"In order to leave your kid out, you have to consciously make that decision," says Kenneth S. Wolf of Hoffman Sabban & Watanmaker of Los Angeles, a firm that specializes in estate planning. Rules for "omitted" or "pretermitted" children "go back to the Middle Ages," he says.

But Crichton's will contains a bit of 20th-century lawyering that may complicate matters. In a provision under the heading, "incontestability," the will states: "I have intentionally made no provision in this will for any of my heirs or relatives who are not herein mentioned or designated, and I hereby generally and specifically disinherit every person claiming to be or who may be determined to be my heir-at-law, except as otherwise mentioned in this will."

Given Crichton's prolific romantic life, this language would seem to block surprise offspring from coming out of the woodwork. After all, another clause states emphatically that Crichton would disinherit any person making a claim under "common-law marriage" or the theory in Marvin v. Marvin, the 1979 case brought by actor Lee Marvin's live-in girlfriend, seeking rights to his property.

To make her case for control of her son's share of the estate, Sherri Crichton has retained Adam Streisand of the Los Angeles office of Loeb & Loeb, a trial lawyer renowned for courtroom victories regarding the estates of celebrities, including Ray Charles and Marlon Brando.

That she has turned to a high-profile litigator may suggest she is gearing up for a courtroom battle to contest the will's language on unmentioned heirs. Streisand did not return several calls for comment, but other lawyers said Sherri appears to have a good case.

Wolf, for one, described the "incontestability" clause as "a pretty standard clause," and one drafted in 2007, long before the infant was born and thus not obviously intended to exclude the boy.

Alan Yoshitake, head of the trusts and estates group at Los Angeles' Seyfarth Shaw, called it a "beefed-up no-contest clause," but added that his "strong belief" is that the omitted-child statute would let the infant share his father's fortune.

At any rate, the child has nothing to lose by contesting away, because he's not a named beneficiary. "The no-contest clause is only useful if you are threatening to take something away," says Susan House of Hahn & Hahn in Pasadena, California. "Here we have someone who was not even alive at the time the will was executed, and that is in fact the whole point."

Ironically, had Streisand, Sherri's lawyer, drafted the will in question, he might have rendered the infant out of luck: In a November 2007 article for The Hollywood Reporter, called "Nine Things Entertainment Lawyers Should Know About Probate," Streisand observed: "Celebrities tend to be prolific in all things, including having children out of wedlock."

To avoid heirs claiming their share as omitted children, Streisand wrote, a will or trust should "very specifically" indicate a "clear intention" not to provide for any child not named, "no matter when that child may be born (before or after the execution of the document.)"

Lucky for young John, Crichton's estate lawyer was not Streisand but Burton A. Mitchell of Jeffer Mangels Butler & Marmaro in Los Angeles. Mitchell did not return repeated calls for comment.