I'm sure this has been asked before but here go's.
NFHS rules.

A1 has a break-away layup, B1 runs him down and slaps the backboard intentionally after the shot has been released.

I know this is a technical but does the basket count if it goes in or is it a dead ball. Two shots and sideline.

The ONLY foul that causes a shot to become dead is a player control foul.

This can be called a T, depending on severity and intention. The basket will count if it goes, this could also be called basket interference if it is determined the basket moved enough to cause the ball not to go through the basket.

Not true.

Why not

Say the ball is on the rim when the backboard is slapped hard enough to push the whole structure, causing the rim to move. Is this any different from pulling on the net or the rim itself when the ball is on the rim?

...read definition of basket interference. It doesn't say that.

4.6.4 says "pulls down a movable ring," which I realize doesn't include slapping the backboard, but the cause and effect are the same.

The cause and effect may be the same in your eyes, but unfortunately the rules don't see it the same way that you do. To have BI, you <b>have</b> to touch either the ball or any part of the basket. If you don't touch one or t'other, the rules say that you can't have BI.

....provided it isn't a game played under NCAA Mens rules.... :)

What does the original post say? NFHS rules.

Cause and effect have nothing to do with it. You won't find the words "slapping the backboard" under the B! rule. Therefore, it is not BI.

For anyone who hasn't been in this situation yet:

It is a cop out and totally wrong to call this BI! I have seen this done several times and it is one of my pet peeves. DO NOT CALL BI. THERE IS NO RULE TO SUPPORT IT!

Sorry for yelling but I hate this and the guys I've seen do it are basically afraid to call a T.

So in your humble opinion that is not a good reference to this to be call an basket interference. So what would be the determining factor so it could be call or not.

The determining factor is if the player pulls down the moveable ring and it strikes the ball before it returns to its original position.

Just like the rule says IIRC.

Al, the determining factor is the definition of basket interference. That's why mj said to read it. The definition tells you exactly what basket interference is, and hitting the backboard is not in the definition. Therefore, it is never BI to slap the backboard in HS or NCAA.