If a person comissions a Torah to be written, pays for it, and then publicly donates the Torah to his shul, what is the HalaChah concerning his claim that he is still the owner, and wishes to take it with him when he moves to another location ? I understand that the matter is dealt with in Tractate Megillah , but I am not sure where. What is the general rule oncerning ownership of a Torah ?

If the Torah was a gift to the shul, it belongs to the shul. The suggested practice is that if a person wants to retain ownership, he should write a contract stipulating that the sefer is on loan to the shul. It is also proper to contractually obligate the shul to proper safety precautions, insurance, etc., though sometimes the owner assumes these obligations. In any case, when there is a dispute, a halachic authority must be consulted to determine the nature of the original transaction (gift or loan).