Let's say hypothetically two men are playing golf on a public golf course.. One man loses his ball in a stream (which is on the golf course's property)... The man goes to collect his ball from the stream and comes back with his original ball and 10 other balls he found that were not his..
Is this man stealing? If so from who? The previous ball owner or the golf course?
This would all be hypothetically in New York state in the United States
Individual lost balls are generally considered to be abandoned property, and finders may keep them unless the golf course specifically forbids it as a matter of policy.
However, large scale recovery of lost balls is a different matter. For example some courses may pay divers, or have other means of collecting large quantities of balls from water hazards, and then resell them to recoup costs. In such a case they wouldn't allow you to go fishing for more than just the ball you lost, presuming it can be reached from the shore.
Your example of 10 balls from the stream is somewhere in the middle, but in any case it is unlikely to be considered criminal theft unless there were aggravating circumstances. (for example trespassing while wearing a wetsuit and carrying a mesh bag full of balls...)
This link from another user illustrates a case where apparently there was theft charges against non-customers with intent to benefit from gathering balls: Golf Ball Theft Case in England
A paying customer, playing a round of golf, who in the act of recovering their own ball simply gathers a few extras within reach without slowing down the game for others is unlikely to be charged or prosecuted for theft. Because it's just as likely that they have also lost balls in the past, and some might actually be theirs if they play the same course regularly...
… but it’s unlikely to be theft
A person steals if he dishonestly appropriates property belonging to another with the intention of permanently depriving the other of it.
With found goods, to avoid a claim of dishonesty, the finder must be able to demonstrate that they made reasonable efforts to find the true owner. For things like golf balls, reasonable efforts is pretty low - first, the value does not justify more than a perfunctory effort, second, the true owner has no way of proving provenance.
On any reasonable interpretation of the facts, the golfer lacks the required dishonesty.
The law recognises three types of property:
Property is not a thing (tangible or intangible) - the thing is the thing. Property is a right over a thing; in Yanner v Eaton, the High Court of Australia said:
The word ‘property’ is often used to refer to something that belongs to another. But … ‘property’ does not refer to a thing; it is a description of a legal relationship with a thing. It refers to a degree of power that is recognised in law as power permissibly exercised over the thing. The concept of ‘property’ may be elusive. Usually it is treated as a ‘bundle of rights’.
The 'bundle of rights' differs for different property types and situations. For example, while a right of occupation makes sense for real property, it makes no sense for a golf ball. Similarly, the right of possession makes sense for a book but not for the copyright in that book.
So, just focusing on the golf balls. Our intrepid golfer has possession of 11 golf balls and 'true' ownership in just one of them.
As discussed above, a person in possession of things that they do not own has a legal duty to find the 'true' owner. For golf balls found on a golf course, this is probably satisfied if you ask around.
Armory v Delamirie [1722] EWHC J94 established that the possessor of an item has a better claim to ownership than anyone but the 'true' owner. This holds for real and personal property, but, as previously mentioned, you can't possess intangible items.
Where you find it also matters, as the owner of the real property where the personal property was found may have a better claim depending on the nature of the property. See Bridges v Hawkesworth, Silcott v Louisville Trust, and Parker v British Airways Board. It may be a condition of play on a given course, or a court may imply such a condition that balls left on the course belong to the golf course; this would be a legitimate transfer of title, and the golf course would be the 'true' owner.
Notwithstanding, a 'true' owner would have to prove their ownership.
For some items, like land, motor vehicles, ships, shares, etc., there may be a public register that presumptively lists the 'true' owner. I say "presumptively" because mistakes and fraud do happen, and registers may be challengeable.
For most items, the 'true' owner would need to prove that they were the 'true' owner on the balance of probabilities. Testimony, receipts, and photos of the person being in possession are all the sorts of things that might be used as evidence of this.
Of course, no one is going to go to this trouble for ten used golf balls.
I think it is possible that this would legally constitute stealing.
The man does not have a property right to the golf balls (other than his own).
Before the balls were collected, they were on the premises of the golf course. The question then is, at that point was the golf course legally considered to be their possessor (even if not necessarily their owner)? If so, the prior possession by the golf course would make it potentially theft for the man to take them without the permission of the golf course. A similar case I saw some references to, although in England rather than New York, is Hibbert v McKiernan [1948]. It seems that in this case, the golf course was ruled to be the possessor of the golf balls at the bottom of a lake on the course. Some notes I found online state that it was viewed as relevant that the balls were stuck in the mud and thus 'fixed to the land'. It might also be relevant if the golf course has taken actions showing that it asserts some level of control over the property. On the other hand, the fact that the golf course is open to the public in the scenario that you describe may act against its ability to assert a right of possession to the abandoned golf balls on its premises (Hibbert v McKiernan dealt with a man trespassing on a private golf course).
If golf course was the possessor, and the man intends to permanently deprive the golf course of the golf balls, while knowing that he does not have a right to the property and that he does not have the permission of the golf course to take the balls, I think this could fall under "common law larceny by trespassory taking". This does not require that he (or anyone else) know who the rightful owner of the property actually is, other than that it isn't him.
All of this notwithstanding, if the man believed, correctly or incorrectly, that he had a right to the balls (e.g. if he thought he had permission from the golf course to take them; or possibly if he thought that by finding them he was their rightful owner) he would not be guilty of stealing them because he would lack the necessary criminal intent.
