I noticed on the post about the drug lord that in his collection, he had pieces of artwork that were "illegal to own." What kind of cultural or historical significance would make an item illegal to own? What would be some examples of this?
Not illegal to own, but a 1940 federal law in the US makes it illegal to sell stuffed bald eagles. This lead to a dispute over the value of a piece of art called "Canyon," which included a full, stuffed bald eagle. The owners, who inherited it from their mother after she died, claim that it's worth $0 and thus not subject to any tax, because it cannot be sold. The IRS begs to differ. More details.
It is illegal in most jurisdictions to possess stolen property, there are federal laws in US governing rhe acquisition possession of objects of cultural or religious significance, especially Native American relics, and other such things. The most common problem are the stolen art works looted by Nazis, but similar problems arise with regard to cultural artifacts illegally exported from Central and South America, which might be the issue for the drug lord. . . . I doubt that "illegal" was used with any precision in that post.
The first laws regarding antiquities exports first began to appear just before 1900 and then were adopted by individual countries, each with their own laws and regulations.
International laws on cultural property rights were finally created by the 1954 Hague Convention which made a common definition of cultural protection, and each country of origin had its own right to protect and maintain their cultural material heritage with special protection awarded during times of conflict.
Full-scale regulations were enacted in 1970 by the United Nations’ Convention on the Means of Prohibiting the Illicit Import, Export and Transfer of Ownership of Cultural Property wherein international antiquities sales were legally forced to provide legally registered provenances for each item in the open market, and outlaw the sale of any antiquity post that year.
UNESCO. "Convention on the Means of Prohibiting and Preventing the Illicit Import, Export and Transfer of Ownership of Cultural Property 1970." http://www.unesco.org/new/en/unesco/. November 14, 1970. http://portal.unesco.org/en/ev.php-URL_ID=13039&URL_DO=DO_TOPIC&URL_SECTION=201.html
Basically, if an artifact or antiquity was part of a collection prior to 1970, then they can be bought and sold on the open market as long as they have the proper paperwork to go with it. This gets abused like nothing else. Forged paperwork is not that hard to create (although there are now crackdowns). Anything discovered or dug up after 1970 is illegal to sell. Illegal digging (especially in Iraq) is rampant, and that's not including looting from museums/private collections . Here's a big field in Iraq showing the pock marks of digging: http://www.csmonitor.com/World/Middle-East/2008/0520/p01s04-wome.html
There are three markets in this: white (the legal sales you see at places like Christies or Sotheby's*), grey where antiquities can sort of bounce around legal and illegal sales, and the straight up black market. These can be small scale dealers who sell from the diggers to middle men to middle men to collectors, or they can be run by various criminal organizations. It's why Italy has a lot of resources dedicated to fighting antiquities theft.
*Btw, Christies, Sotheby's, and even the Getty Museum have all been dinged hard in the past for selling/buying stolen and improperly documented antiquities/artifacts. Now a lot of these sales have gone online, so it's that much harder to track things down, especially if these items are being shipped from say Jordan=>Spain=>Belgium=> America (or China or South America or wherever).
Germany has restrictions on Nazi memorabilia, artwork, etc.
Perhaps not artwork, but in a lot of countries it might be illegal to own rare eggs from birds, ivory etc.
In Sweden all rune stones are owned by the state, so even if you have one in your back yard (yes, it happens) you are not allowed to move it, damage it, sell it etc. So, you are certainly not allowed to have a rune stone in your living room or something if you somehow managed to get hold of one. So, if you consider rune stones art (I do) it is illegal to own one, at least in Sweden, and most likely the other Scandinavian countries too.
Japan for instance has very significant restrictions on the ownership of historical katana and other blades. There is a sense that the old swords are of very great cultural and historical significance and the nation prefers that the swords stay in Japanese hands and in-country.
These cultural relics can leave the country for museum display and other reasons and there is a large secondary market for those that want to own swords to get proper paper-work completed. My (limited) understanding is that this usually this ends up being a situation in which the sword is technically or legally in care of a museum and owned by a private individual, but for all intents and purposes is both privately owned and displayed.
This brings up a larger point about relics, art and the law. In the case of weapons and other dangerous relics, when is it a dangerous and restricted item and when is it a cultural relic or artifact? How does the law treat someone with an old Beretta flintlock or a civil war revolver or a medieval falchion... Here every nation has differing laws on what you can own, how you can store and display it and what your legal registration and care needs to be like.
Some artworks containing parts of endangered species are illegal to own.
I know Native Americans have special permission to get eagle feathers that are used in religious/cultural ceremonies.