It's amazing what you find in the BOOK...

[SamNVa]

I happened to be perusing the nether regions at the back of the FED rule book this afternoon and came across the following passage:

Points of Emphasis (p.78)
Three Foot Running Lane

In all situations when the batter-runner
is entitled to run (i.e. a batted ball, base on balls,
or dropped third strike), she must use the
three-foot running lane. An award of first base on
a base on balls does not negate the requirements to use
the three-foot running lane. If the batter-runner steps
out of the lane, she is subject to being called out (8-4-2n).
(Emphasis added)

So the ruling has been right there in the book all along.