At NSA states 12u. Runner trying to score from 3rd.Ball, catcher, runner all at the plate at the some time. Catcher holds on makes tag. girl never made it to the plate. Great play by the catcher. runner out. Wait, runner safe. obstruction by the catcher. (ch)ump says you can't block plate without the ball. you make the call.
Okay, I'll confine my answers to the first post, lest I invoke the wrath of "the clue"...
You didn't provide enough information to "make the call".
Questions: Prior to the catcher gaining possession of the ball, did the catcher blocking the plate cause the runner to in any way alter her path to the base? Did the runner have to slow down? Did she have to attempt to go around the catcher? Did the catcher contact the runner?
Answer us that and we might at least be able to give you an opinion (though it will be an opinion based on second-hand information from someone who obviously has an emotional bias in the outcome of the call).
Just going on what you did tell us, the explanation you got was only half-right. Contrary to what most people think, it IS NOT illegal for a fielder to block a base. Obstruction requires TWO elements. The first one is for the fielder to block a base without possession of the ball. The second element is for the runner to actually be impeded in some way. You need BOTH elements for an obstruction call.
It is entirely possible for a fielder to be blocking a base without the ball, but for the runner to never slow down, go around or otherwise deviate from her chosen path to the base. In that case, then the runner was not obstructed.
So...did the runner have to alter her basepath BEFORE the catcher had the ball? Then I would call this obstruction.
If the runner did not have to alter her basepath, I would not have obstruction- no matter where the catcher was set up.