SAN FRANCISCO —Faced with aging precedents from arcane disputes over hunting, whaling, and even sunken treasure recovery, a judge handling the case of two California men who claim to own Barry Bonds' record 73rd home run ball considered holding a debate Tuesday featuring experts on the subject from both sides.

The central issue: When does someone have lawful possession of an object that was not previously owned?

On Tuesday, San Francisco Superior Court Judge Kevin M. McCarthy and the legal teams for Alex Popov—who first got a glove on the Oct. 7, 2001, home run—and Patrick Hayashi, who came up with the ball after a melee—agreed that while some precedent existed, the acts of shooting a fox with a musket, harpooning a whale, or raising a treasure-laden galleon were not exactly analogous to the act of catching a home run baseball.

So the group posed an interesting solution: Why not allow the leading experts in the field to debate the issue in an open-court cross fire? That way, the question of just what constitutes possession in the bleachers, a novel legal quandary, could be distilled in one concentrated session.

The debate, which would take place in open court, would include experts from both sides. Popov's lineup would consist of three experts, including the only published authority on the subject of home-run baseballs, University of Tulsa law professor Paul Finkelman. Hayashi would be represented by another heavy hitter, the dean of the University of California Berkeley Law School, John Dwyer.

Judge McCarthy has yet to set anything in stone, but the prospect of a debate was well-received by both sides. "I love it," said Martin Triano, Popov's lawyer. "It's just a great idea." Donald Tamaki, Hayashi's lawyer, agreed. "There's never been a baseball case," he said. "Our view is it's not enough to say 'I was there first.'"

Popov, 38, a health food restaurateur says he caught Bonds' historic homer on Oct. 7, 2001, and held onto it in a pack of fans until it was torn from his hands. Hayashi, 37, a software engineer from Sacramento, claims that the ball rolled loose and he plucked it from the ground. Popov is suing Hayashi for the ball, which has an estimated value of $1 million.

Since the wrangling over the ball commenced more than a year ago, Popov and his lawyers have cast the trial as more than a simple property dispute, calling it a battle between right and wrong. They say Hayashi clawed his way to the ball and wrenched it from Popov's mitt.

But Hayashi has maintained that he merely plucked the prized ball from the ground. According to Don Tamaki, Hayashi's lawyer, the assault allegations are "reckless" attempts to malign his client's character. "It doesn't surprise me that they've taken that strategy," he said. "The evidence of this so-called assault and battery is extremely weak, and that's why it was thrown out in the first place."

But Hayashi's conduct in the pile-up will be a question for the trial judge to ponder. On Tuesday Judge James McBride, who was handling pretrial motions in the case, reversed a previous ruling that had erased the assault charges.

According to McBride's filing, "issues of fact exist regarding whether defendant committed or attempted to commit an act resulting in harmful or offensive contact with plaintiff's person."

Triano's said Tuesday that his leadoff witness, scheduled to appear Thursday afternoon, will be fellow game attendee Catherine Sorenson, who allegedly saw Hayashi "mining" for the ball in the pack of fallen fans.

Bonds' 73rd home run may have been the highlight of the Giants' otherwise lackluster 2001 season. But while Popov and Hayashi scrap over the spoils of a season gone by, the team has gone on to greater conquests. On Monday, the Giants gained their first World Series berth since 1989 after defeating the St. Louis Cardinals to win the pennant.

In the stands was Alex Popov. Like a year ago, he said he came to Pacific Bell Park to see history—but this time, he added, "I wasn't there to catch a home run ball."

Opening statements are expected Wednesday afternoon.