You’re all set to buy a painting. You like the way it looks and the price is right. But one question remains: Can the seller prove it is by the named artist and not a forgery or misattributed?

It’s a crucial question. Proof of authorship is essential if one day you want to sell the piece. If a private buyer, gallery or auction house questions the work’s authenticity, it may become unsellable, and your money lost.

So-called...

You’re all set to buy a painting. You like the way it looks and the price is right. But one question remains: Can the seller prove it is by the named artist and not a forgery or misattributed?

It’s a crucial question. Proof of authorship is essential if one day you want to sell the piece. If a private buyer, gallery or auction house questions the work’s authenticity, it may become unsellable, and your money lost.

So-called authentication committees exist, usually established by an artist’s estate and composed of people knowledgeable in the artists’ work, to verify attribution. But many have disbanded in recent years, often due to costly legal battles when a committee would not approve a work as authentic.

Given that, if there is no authentication committee, how can buyers minimize the risk that they aren’t buying the real thing?

These are the questions to ask the seller, and if the seller doesn’t have the answers, you should find them out yourself:

• What is the provenance? A paper trail ideally should provide a clear and unbroken chain of ownership from the artist’s studio to the present owner’s wall. One might consist of diary and museum catalogue entries, receipts, photographs and statements by people who knew the artist and saw the artwork, such as friends, family members and dealers.

• Has the work been officially recognized as being part of an artist’s body of work, known as a catalogue raisonné?

• Have any recognized experts in the artist’s work (art historians and museum curators, for instance) attested to its authenticity?

• Has any scientific analysis attested to the work’s originality? Tests include physical analysis of paints and canvas, X-rays, infrared and ultraviolet lights and magnetic resonance imaging. In some cases, artificial-intelligence software has been used to learn the main features of an artist’s work and confirm whether similar features are present in the work being examined.

Next on the checklist, a purchase must include a written agreement (not just an invoice or receipt). Megan Noh, co-chair of the art law group at the New York law firm Pryor Cashman, says such an agreement should include unqualified representations from the seller that the work “is authentic and that the seller has provided all information in its possession about the work relevant to attribution, including any prior third-party authenticity opinions.”

Under the Uniform Commercial Code, a model code pertaining to commercial transactions from which relevant provisions have been adopted in 49 states and the District of Columbia (Louisiana is the outlier), a description of artwork that includes the artist attribution creates an express warranty. However, Ms. Noh states that “the UCC simply establishes a contractual cause of action in the event of a breach of warranty but does not specify a method of dispute resolution for such a claim.” This means that in case of a challenge, the decision as to authenticity likely will have to be litigated unless the relevant purchase contract sets forth another mechanism, such as arbitration.

The costs of litigating an authenticity dispute can easily reach the hundreds of thousands of dollars, with the final decision made by a judge whose opinion might not be accepted by the art market at large.

For extra protection, a buyer might demand that a purchase agreement include a rescission clause that obligates the seller to take the artwork back and return the buyer’s money if a negotiated “trigger” event occurs, such as an adverse opinion by an authentication or catalogue raisonné committee.

Mr. Grant is a writer in Amherst, Mass. He can be reached at reports@wsj.com.