and how does it apply to you?
The Visual Artists Rights Act of 1990 (VARA) is a law in which Artists are provided a few special protections in reference to the works they create. These protections are in addition to normal copyright laws that apply to all original works.
Copyright law provides that the originator (artist) retains all rights to copy or reproduce that work. While works of art may be formally registered with the Library of Congress, all newly created works of art are protected under US Copyright law at the time of their creation. In short, the artist owns the right to make copies, or authorize other parties to do so. The artist also has the right to not make any copies or to bar others from making unauthorized copies. Copyright protections also extend to derivatives of the original-- modified or customized versions of the artwork, whether the modifications were made by the original artist or another party.
There are exceptions to basic copyright law, when it comes to work made for hire or works created as part of one's employment. Contracts can also be written that specify copyright ownership that may vary from the standard "default" laws.
Copyrights can be sold, leased, licensed, given away, willed to heirs and waived as the holder of them chooses. Copyrights are valid until 75 years after the artist's death, then the object becomes part of the "public realm".
"Visual Arts" in the VARA context encompasses primarily fine art, such as sculptures and paintings, and ONLY applies in the case of a singular original or when there are 200 or fewer numbered copies (as in a limited edition) made. By law, such pieces that qualify are considered 'rare' and therefore have some type of intrinsic value of their own by virtue of that fact. The VARA provides that an artist has the right to insist that artwork which falls under this law is not modified or altered in any way, more or less to preserve the integrity of the piece (or edition), the artist's vision and so forth. VARA does not apply to restoration/preservation measures.
In the context of Resin Horses, the sculptor of the original maintains all copyrights and since most resin editions are produced in numbers fewer than 200, VARA may come into play as well. In short, an artist may have the right to insist that copies of an edition are not modified, or are modified only to the degree the artist chooses to allow. It is common courtesy and generally safe to assume when dealing with any completed piece (painted and finished, requiring no additional work) that if for some reason the owner may wish to have the piece modified, permission should be sought from the artist(s) involved before proceeding.
In the case of 'bodies' (unpainted pieces) sold with the intent that someone other than the sculpting artist will finish them, if the sculpting artist's policies are not explicitly stated, then the artist should be contacted prior to making any modifications. For the most part, most pieces sold as unpainted "to-be-finished" bodies, the sculpting artist expects that some modifications to the sculpture itself may be made before the piece is painted. If in doubt, simply take the time to contact the artist and ask. At the very least it will prevent any hard feelings or misunderstandings over the long term and its just polite common courtesy to boot. While Resin Horses may often be bought and sold as collectibles, they are also undoubtedly art... the product of the original vision and expression of emotion of the creator.