Player A makes a successful rescue attempt against player B. Player B begins to hand a soul over, then changes his mind and decides to give a different soul, and begins to withdraw his arm. Player A snatches the card from Player B, and player B protests.
Player A's argument is that Player B picked up the soul, and his hand was halfway across the table.
Player B's argument is that he did not hand Player A the soul, and his hand had already begun to withdraw at the point that Player A took it from him.
Assume this is at a national tournament, so there's no exceptions being made for anyone. Is this a case where Player B made a mistake and has to own it, or was he still within his rights to change his mind until he handed the card over?