Runner's 1st Base vs Fielder's 1st Base

Within the last few weeks sometime, there was a disputed call at first base and apparently some confusion over the use of the orange base in foul territory.  I thought it might be educational for everyone to review the actual rule.  

The secondary first base which is in foul territory belongs to the runner only.  The defense can only make an out using the white bag that is in fair territory. However, the base runner can be safe by using the white bag if he does so in order to avoid a collision.  This collision avoidance exception is, of course, up to the judgement of the umpire.

Here is the rule excerpt.

8.4 AFTER GETTING A HIT
8.4 (1) BATTER/RUNNER REACHING FIRST BASE
Each batter must reach first base without the aid of a courtesy runner. 
A Double Bag shall be used at first base, the double portion of the bag
being in foul territory abutting first base.  If there is a play on
a batter/runner going to first base, the batter/runner must touch the
portion of the Double Bag extending into foul territory. He will be
called out if he fails to do so, except, in the umpire’s judgment, the
batter-runner is avoiding a collision.  This is NOT an appeal play. 
Important: The defending player has only the white base, in fair
territory, to make the putout; his touch of only the bag in foul ter-
ritory will not result in an out.