Coach teaching bad tactics.
 

My 8th grade grand daughter told me her coach is teaching them to trap an A1 player along OB while making sure they are stepping on the OB line so that if A1 makes contact with them they will get the ball. But I told her no and cuz she wants more proof I said ok, its not only me, I know a bunch of other refs who would agree. So will ya help us out? Gonna share it with coach too.

Sure, if a player is touching the out of bounds line, that player is out of bounds and not in legal guarding position.

Contact creates a found on the defender.

This may help

Nice try coach, but...
 

Also, if a defender has a foot on a boundary line he/she cannot obtain LGP so if the player with the ball runs into one of those kids it's a block on the defense (assuming, of course, the offense player didn't do anything that would result in an intentional or flagrant foul).

Good way to get fouls on your players. The defensive player loses legal guarding position when they place a foot OOB, thus all fouls are their responsibility.

Sounds like this coach is ready to move up a few notches. :rolleyes:

Easy enough...

A player who has any part of their body touching out of bounds is out of bounds (4-35-1, 4-35-2, 7-1-1)

If an out of bounds player touches the ball, the ball is out of bounds by virtue of being touched by said out of bounds player (7-2-2)

An out of bounds player cannot have legal guarding position (4-32-2)

So, to summarized for upanddown,

While your daughter's defender is OOB, the following is all that can/can't happen...

1. They're likely responsible for the contact if there is a block/charge decision (they could still get fouled in a few ways).
2. If A1 does touch them and it isn't a foul, it doesn't cause the ball to be OOB at all so they don't get any benefit from doing it in that area. To be OOB, A1 has to touch something OOB other than another player.
3. If A1 touches them with the, they will have caused the ball to be OOB letting A1 effectively out of the trap with a new throwin for team A.

So, it is a lose-lose strategy. Best to stay inbounds.

It is not accurate to say all fouls are their responsibility.

Back before this rule changed, my college coach used to teach cutting off baseline drives by having one foot on the baseline or OOB.

Now that the rule has changed, that's no longer legal. ;)

He's coaching HS Freshman boys now, so I made sure to remind him that this rule has changed since he last coached.

Three Feet ...
 

Maybe the coach is confusing, misunderstanding, or overemphasizing, this rule:

4-7-2-C: There must be reasonable space between two defensive players or a
defensive player and a boundary line to allow the dribbler to continue in
his/her path. If there is less than 3 feet of space, the dribbler has the greater
responsibility for the contact.