On some of the Knife Forums, the ivory ban that goes into effect on July 6, 2016 is the source of a lot of discussion and concern.
Here is an analysis from Knifetalk Forums posted by a member that is a lawyer:

"Possession.
-Personal possession and non-commercial use (including non-commercial movement within the USA) of legally acquired ivory is permitted.
-The new rule does not impact or change the existing personal possession and non-commercial movement rules which have been in effect since 2014.

Commerce.
-No commercial importation of African elephant ivory is permitted (whether or not it is an antique).
-Non-commercial importation of African elephant ivory is permitted only under very limited circumstances (e.g., part of household move or inheritance; musical performances; traveling exhibitions; etc.).
-No interstate or intrastate commerce of an item containing African elephant ivory is permitted unless:
(1) the item qualifies as an antique under the ESA (this will not help Randall owners as one of the criteria for ‘antique’ statuts under the ESA is that the item be at least 100 years old); or
(2a) the item contains a de minimis amount of ivory (this means 200 grams which is 7.05 oz.) or less; and
(2b) the item meets these specifications:
(i) it is handcrafted or manufactured; and
(ii) the ivory contained in the item was imported into the US before January 18, 1990; and
(iii) the ivory is a fixed or integral component of a larger item;
(iv) the ivory does not account for more than 50% of the value of the item; and
(v) the item was manufactured or handcrafted before July 6, 2016.

Notes/Comments:
-This USFWS regulation applies ONLY to ivory from African elephants, and does NOT refer or apply to ivory from Asian elephants, walrus, whales/sea mammals, mammoths/mastodons, or any other animals. There are different rules regarding ivory originating with Asian elephants and other animals.
-This discussion does not include the other non-commercial permitted uses (sport hunted trophies, law enforcement or scientific specimens, worked ivory legally acquired and removed from the wild before 2/26/76 and not sold since 2/25/14, etc.), which have different qualifying criteria.
-International import or export of raw elephant ivory is prohibited.
-Intrastate or interstate commercial trade in raw ivory is permitted if it was imported before January 18, 1990, or it was imported under a CITES pre-Convention certificate. The seller must demonstrate compliance.
-Knives, and guns with ivory grips, are “assumed” to qualify for the de minimis limit. This means that the government assumes the amount of ivory in a knife handle is below the 200 gram limit. Given this assumption, a knife owner should NOT be required to remove the knife handle to be weighed.
-To summarize:
-It is "legal" to own an ivory handled knife if the ivory was legally obtained. The problem is in confirming the "legality" of the ivory. I'm guessing few, if any, collectors can do so.
-It is "legal" to buy and sell an ivory handled knife if the ivory was legally obtained. Again, the problem is in demonstrating the legality of the ivory (proving the circumstances under which it was obtained). This burden is on the seller.
-Given how I've never seen an ivory import certificate, even with items sold by famed auction houses, good luck proving that the ivory is non-elephant or otherwise qualifies as legal. Short of a DNA test or expert certificate, how could you re-create lost (or never existing)paperwork? Small wonder that most ivory handled knifes (and other items) are offered for sale as mammoth or fossil or walrus ivory or some similar material. Even salvaging an old ivory-keyed piano for it ivory will be problematic without paperwork."

The net result of the comments seems to be enforcement could be arbitrary and may cause seizure that results in an owner being required to prove that the ivory is legal.