Elementary Question

[rotationslim]

I have been tapped to run a Church Basketball Program (LDS Church in Michigan) We have an adult and teenage league.

I am inexperienced, and we recruit volunteer dads and others to referee. We have fun, don't have too many problems. But I need guidance on how to call foul's underneath. We follow High School rules, (but quality of play is probably lower rec-ball), but can anyone give me a rule of thumb for calling fouls underneath the basket.

If we called every bit of contact we would be blowing the whistle all night. Should I, and my other inexperienced ref's just blow the whistle on any major contact, and call it on the defense, (if it isn't obviously on the offense.)

As I think about it, my problem is I have been brought up in the US, where our system of justice is "Beyond a reasonable of doubt" so I find myself looking for the absolute visual proof of a foul, before I blow the whistle. What I sometimes end up with is 2 guys no the floor after a collision, and me not making a call. I see the evidence of someone's foul, but not knowing who to call for it. Any elementary tips for untrained volunteer ref.
(Obvious answer is get trained, but that is not an option, at least for this season)