Is there a rule about the angle at which your arm can be held? (The angle being that between your upper arm and the vertical.) Swear I've heard that from somewhere.

Isaac, I've heard this too as 45 degrees... can a ref confirm or deny?

Basically he/she's allowed to hold the arm bar there to protect the dribble, as long as it's not pushing the defence away or 'fending off'. 45 degrees is a general rule - high enough to protect the dribble and still low enough that it can't be used to hold the defence away. It must be HELD - as soon as the forearm is extended at all it is a foul.

In regards to the defence, it depends what situation you mean. No hands are technically allowed on the dribbler but unless the offence is disadvantaged then it probably won't be called. Just make sure you listen to the ref, he/she will most likely yell at you to get your hands out before they call a foul. 2 hands on should be considered an automatic foul.

For a post player 1 arm bar is allowed in the back but as soon as the offence turns and faces this must be removed. Again the 45 degrees is a general rule here, and again 2 arms is an automatic foul. Just listen to the ref though, most times they will tell you a few times before they call it

If by fending them off you mean pushing them away then no. If you established your arm bar without pushing them (or hitting them in the gut etc) then this would be ok (general rule 45 degrees with no extending of it).

The offender has priority unless the defence LEGALLY gets in their way (or the offence goes out of their normal motion - ie extending their forearm or dropping a shoulder to deliberately make contact).

If the offender uses the arm bar to protect the ball without going out of their normal motion, and without making (significant) contact with a legal defender then that's ok

Hope that makes sense :)

So if you can only hold an arm bar at 45 degrees in order to post up offensively. How are you supposed to establish and hold post postition when the defender is able to lean all over the post player with two hands in the back?

The rule should be 90 degrees for the arm bar in the post. It's ridiculous that all the advantage goes to the defender in that situation.

I think the angle is for the defensive player, not the guy with the ball. And I don't think they can have two hands in their back. Can a ref provide a bit more info?

Not to move away from the threat title (but so closely related) I am a little confused as to when a defensive foul cannot be called from the offensive player entering the defensive players cylinder.
What I read in the rules pertaining to 'established legal guarding position' leaves me with this question,
Defender in the key in a legal position, arms raised above head with slight bent elbows, ball carrier drives to the basket from infront and attempts to come around defender but both players arms contact when the shot is made. Is this a defensive foul?
Basically after trying to get a better grasp on the rules due to fill-in umpiring, I am noticing more that these situatuions are resulting in a foul.
Thoughts?

Wait so I have a question about arm bar if I am dribbling and I have my arm extended out towards a defender to create space is that illegal. Also if i use that same arm to go in side by pushing my defender is that illegal.

Hi Guys, I know I'm a bit late on this but I'm a ref and am happy to explain the armbar rule. In regards to post play, a single armbar is legal but if the opponent turns in any direction the hand must be removed. This goes for a player with or without the ball so long as the player isn't holding or pushing off the player. If 2 hands are used, it's an automatic foul. For a player dribbling the ball, they can not extend their free arm to prevent the defence of a legal opportunity to steal the ball. By FIBA, if any contact is made an offensive foul must be called but of course in junior and lower ranked leagues, refs will try and prevent this from happening by using their voices. The 45 degree principle, is not in the current rulebook (2017) but may have been in the past. For dribblers, the best thing to do is not extending that free arm. So for junior coaches, it's essential to remove that habit before kids get too use to it.