RE: Can a customer take IP's with them?

From: Vincent J. Bono
I think one avenue of approach will be to see if
ARIN would grant you another contiguous block to
replace not just what the customer got but the
entire block they have polluted.

Edward B. Dreger
I thought of that, too. However, that would require
NAC renumbering an entire /17 because an ex-customer
is too lazy to renumber a /24.[*] If NAC's ex-customer
thinks renumbering a /24 is excessive, what about
something two orders of magnitude larger?

Indeed, but that's not the worst part. Should this happen, it would mean
that the ex-customer just got PI space for free. Then the floodgates
would open and a bunch of "why-not-me-too" would sue their ISPs to
transform their PA block into a free PI block.