problably not much. It just seems that, like many laws already on the books, are either not enforced or simply ignored (at least from China or overseas). It just seems that counterfeiting and other sleazy dealings are on the rise, despite any laws that may be on the books.
ebay does not seem to have an effective method of responding except for pulling the listing and possibly banning the seller, who sometimes just re-registers in a different account.
my "law" would require local and overseas (read: China mostly) sellers to have their coin certified by a US-based agency that the buyer could contact toll-free prior to buying the coin.
And any VERIFIED/SLAM-DUNK GUILTY fraudulent
ebay sellers would be AUTOMATICALLY referred by
ebay to this SPECIFIC agency formed solely and for dealing with counterfeit coins only, and that this agency would have the full cooperation of all nations, especially Chinese and other governments. (figure the odds on that, unless we gave China millions of dollars to cooperate).
We could get the U.N. to pass a worthless and useless act or "resolution". everybody knows that the U.N. scares the pants off of every nation, right?

or, only give them money on the criminal transactions that they do move on, a case-by-case system. (I am sure the US taxpayer would love this, but we already give away billions each year on totally worthless and ineffective causes). Government waste is at an all-time high, so why not add to it, with the exception being that this would not be a wasteful cause... at least not to us.
There would be raids and arrests by the hundreds and maybe people would get the idea that conning people on coins is no longer a game where arrests are few and convictions even fewer, especially if a few convictions are widely made public with heavy fines and lengthy jail sentences.
So how practical would it be for Chinese sellers to mail their coins to the US for the certification prior to their sale? not much.
How practical would it be for you to have to mail in or run down to an agency that may not even be in your town for a certification for a coin you want to sell? not much.
so maybe that is not practical. I do not know which particular law you are referring to, but regardless it just seems that bad sellers seems to be a semi-regular event, despite what is already on the books.
Exceptions or exemptions could be made for NGC coins that are verified through their tracking site, as they already have. Require the other major graders to do the same.
As a precaution, I run NGC holder serial numbers through their description page, which provides a description and most (but not all) of the time some photos of your coin. but even they can and do make mistakes, I have had to have corrected several of them by NGC.
I am not saying I have all the answers, but it just seems to me that more COULD be done. I am not saying that I am right about this though... I am just suggesting that a PREVENTATIVE measure might be something good if it could be made practical. I am not saying I am right or being realistic though...
but, I agree, it is best or most effective for the buyer to be educated and not allow themselves to beome victims in the first place. but is this possible in every case until it is too late?