A trial in San Francisco will decide who owns the baseball, said to be worth $1 million dollars, that Barry Bonds hit for his record-setting 73rd homer. Is it Alex Popov, a fan who appeared for a split second to catch it, or Mr. Hayashi, a fan who ended up holding it after a scramble?
"I caught the ball. I possessed it but then I was mugged," said Popov.
"I plucked the ball from the ground after being pushed there by the mob," said Hayashi.
The videotape does seem to show Popov snag the ball for a split second on the fly, but it is impossible to tell whether he still had the ball before tumbling beneath a crush of frantic fans.
How might Jewish law, halacha, decide this case?
There are situations in which the finder of lost property has no obligation to return it to the original owner and may keep it for himself. One such situation is where the original owner abandons the item, as in the case of Bond's baseball. But what happens if two people are holding on to an item of abandoned property and each claims to have found it first?
There are three possible halachic solutions to the problem.
The first is to divide the object, or the proceeds from the sale of the object, between the contestants.
The second is for the court to confiscate the ball from both parties. 
The third is to require each contestant to do something that demonstrates to the court that he is not lying.
In most situations not involving abandoned property, when the contestants have competing claims which cannot be resolved by evidence, the matter is resolved by equally dividing the value of the disputed object between the parties in accordance with the halachic rule "Mamon hamutal besafek, cholkim," money placed in a doubt should be divided . If this solution were applied to this case, it would encourage people to grab the item from the hands of the original finder and falsely claim that they found it first. They would then enjoy the undeserved windfall of half the value of the grabbed item. The result would be a scuffle similar to the one witnessed on the baseball field.
The second solution of confiscating the abandoned object is equally unsatisfactory because it does not discourage grabbing and lying. After all, neither party will be out of pocket if the court confiscates the baseball, so why not try to grab and lie?
The third solution is for each contestant to take a "shavuah," an oath invoking the name of God that each one owns not less than half the abandoned item . The assumption is that nobody will risk the penalty of Karet, premature death at the Hand of God, which is the Torah's consequence for taking a false oath, for half a baseball and so the truth will out.
Invoking the name of God through an oath is a serious matter. The Rabbis will shrink from employing this "trial by ordeal" solution unless they can find an analogous case in the Torah itself.
Generally, the Torah does not require a defendant to swear that he does not owe the plaintiff money, based on the Torah principle "Hamotze mechaveiro, alav haraeyah," -- the onus is on the plaintiff to prove his case . In the absence of such proof, the defendant walks.
However, there are situations in which the Torah requires the defendant to take an oath in support of his case. One such case is where the defendant is "Modeh bemiktzat," he admits to part of the claim against him but denies the other part of the claim . He admits, for example, that he borrowed $100 dollars but claims that he repaid $50. In this situation, the halacha imposes an oath on the defendant because there is a concern that in fact, he does owe $100 and though he is not brazen enough to deny the entire amount, he is under sufficient financial pressure to deny part of it .
The second situation in which the Torah requires a defendant to take a Shavuah is when the plaintiff produces only one witness to substantiate his claim . Although the rule is that all monetary claims must be supported by two witnesses, one witness establishes enough of a case to require the defendant to take an oath in support of his defense.
Another situation in which the Torah requires the defendant to take an oath is when the defendant denies the whole amount of the claim but the plaintiff then brings witnesses, or there is other evidence, that the defendant owes at least part of the claim . In such a case, according to Rabbi Chiyah, the Torah imposes an oath on the defendant to substantiate his statement that he does not owe the other part.
The fact that the video shows both Popov and Hayashi holding the ball at relevant times is tantamount to the testimony of witnesses that each contestant is at least the owner of half the ball. This situation is sufficiently analogous to the oath the Torah imposes in the second situation mentioned above, to permit the Rabbis to impose an oath both on Popov and Hayashi. After taking the oath, that each would own not less than half the ball, and Popov and Hayashi each would be entitled to $500,000.
 Bava Metzia 2a
 Tosafot Bava Kamma 103a, s.v. "Aval"
 In accordance with the rule of Sumchus, Bava Kamma 46a
 Bava Metzia 2a; Rambam, Hilchot Toen Venitan, 9:7
 Bava Metzia 2b,Rambam, Hilchot Nizkei Mamon 9:3
 Bava Metzia 3a, based on the words "Ki Hu Ze," Exodus 22:8; Rambam, Hichot Toen Venitan, 1:1
 Bava Metzia 3b
 According to the opinion of Rabbi Chiyah, Bava Metzia 3a