What is the rule when fish jump on their own into a person's boat?
A guarded boat functions as a protected courtyard. Fish that enter it on their own are automatically acquired by the boat's owner.
Question 2
If a person takes a fish from a colleague's net while the net is still at sea, what is the ruling?
Though the fish has no owner, removing it from another person's trap is prohibited — the trapper has a prior claim through his instrument.
Question 3
When a person sets a snare in a colleague's field and catches an animal, who acquires it?
The snare-setter acquires the animal. The field owner has no acquisition rights merely from the animal being caught on his land.
Question 4
A person plunges a spade into one corner of a deceased convert's clearly bounded field. What does he acquire?
He acquires only what his single act of possession reached. Clear boundary markers do not extend one act to the entire parcel.
Question 5
When does the sovereign's law (dina d'malkhuta) apply to methods of acquisition?
Dina d'malkhuta applies when the government enforces a specific mode (e.g., written deed for movables). It supplements, not overrides, halachic acquisition methods.