The key for me is “was there an advantage?”.

Examples:

1. A1 drives for a layup and is slightly bumped by B1. (hold your whistle) The shot goes in. No call as there is no advantage.

2. A1 drives for a layup and is slightly bumped by B1. (hold your whistle) The shot DOES NOT go in. Did the bump put A1 at a disadvantage? If yes, call a foul.

3. A1 drives for a layup and B1 makes contact with A1’s arm. (hold your whistle) The shot goes in. No call as there is no advantage.

4. A1 drives for a layup and B1 makes contact with A1’s arm. (hold your whistle) The shot DOES NOT go in. Did the contact put A1 at a disadvantage? If yes, call a foul.

5. A1 drives for a layup. B1 attempt to block the shot, misses but strikes A1 in the head. The shot goes in. Call the foul as A1 was put at a disadvantage with a head blow.

6. A1 drives for a layup. B1 has a legal guarding position, but moves forward colliding with A1 as the ball is released. The shot goes in. Call the foul as A1 was put at a disadvantage with the collision.

7. A1 drives for a layup. B1 jumps straight into the air maintaining verticality. A1 and B1 collide. (hold your whistle) The shot goes in. Either let it go as A1 created the contact or waive off the goal and call a player control foul on A1.

8. A1 picks off a pass from B1 and has an open court to the basket. From the rear B1 swipes at A1 making contact. (hold your whistle) A1 is not phased and continues to the basket. No call as there is no advantage.

It’s all judgement on your part. But remember, when you blow your whistle you may have to explain to a coach or player why. Sometimes it’s just easier to let the play continue.