There's a lot of stuff that's been written on Hawaiian's arbitrary and capricious baggage fee charges, but I haven't see this one specifically. DH and I flew out 12/14 on HA 327 from KOA to HNL using a United FF award (5K vs. 10K miles per ticket with HA). On United's confirmation itinerary, there is a paragraph on applicable baggage fees. Here it is:

Baggage allowance and charges for this itinerary.
Baggage fees are per traveler

In compliance with U.S. Department of Transportation regulations, checked baggage policies for your entire itinerary are determined by Hawaiian Airlines. Visit united.com/baggage for more information.

Origin and destination for checked baggage 1st bag 2nd bag Max wt / dim per piece
12/14/2013 Kona, HI (KOA) to Honolulu, HI (HNL) 17.00 USD 17.00 USD 50.0lbs (23.0kg) - 62.0in (158.0cm)

However, we were charged $25 for checking in one bag. When I pointed to the $17 language, the agent told us that only tickets issued by HA would get the $17 charge; tickets booked by any other airline (meaning United specifically) would get charged $25.

I also filed a complaint with their customer service online, and was told that the $25 fee was correct because United's fee applied (because they were the marketing carrier) and that their fee was $25, so that's what we were charged.

Something doesn't square right. The point is, my ticket states that the charge would be $17, and that is what I should have been charged. Was it HA, or United, that violated the DOT rule on baggage charges?