At our last fall ball game a girl was steeling third catcher tried to make a throw to third however the batter step forward nervously (half a step) in order to get out of the catchers way thinking the catcher was going to the back side of the plate. The catcher goes to front side of plate, and does not make throw claiming the batter was in the way. The umpire calls runner out for catcher interference. I would think that catcher would need to work around batter on a slight move however it was claimed that batter was doing it intentionally.
"Intent" isn't really relevant to judge interference on this play. A batter may accidently interfere and it's interference just the same.
The first question to ask is, "Did the batter move from her normal batting position?". If "yes", then you have the potential for an interference call.
Second question: "Did the batter's movement impede the catcher making a play?". If "yes", then you have interference.
Generally, in order for it to be judged that a play was impeded, the catcher is going to need to at least attempt a throw- that is, demonstrate in some way that she was actually making a play. If she just stands there and holds the ball, what's to say that she didn't throw because (take your pick) she didn't have a good grip on the ball, or didn't think that she could get the runner, or didn't want some other runner to advance. Absent an actual throw, there needs to be some evidence that a throw was coming, for example cocking back the arm or stepping toward the base, and that it was aborted due the batter's movement.
