“I own the photos.”

It seems like a simple statement, but in copyright law, ownership isn’t simple. One person can own physical photographs, but not have the right to use them, because someone else owns the copyrights.

That distinction is the heart of a case being fought in federal court in Chicago, over the treasure trove of photographs taken by Vivian Maier, whose street photography became known and famous only after her death.

According to the lawsuit filed by her estate, Ms. Maier spent most of her life working as a nanny. Her photography was never professionally shown or exploited in her lifetime. In fact, most of her photos were never even developed during her lifetime.

After her death, collectors found some of her prints and negatives, and after some were published on Flickr, they went viral, generating critical acclaim and wide interest.

There have since been exhibits, books and documentary films about her photos, most of which portray the people and architecture of New York, Chicago, and Los Angeles.

You might think the collectors who own those prints and negatives are in a great position. But they merely own prints and negatives. And section 202 of the Copyright Act states a basic rule that ownership of a copyright “is distinct from ownership of any material object in which the object of the work is embodied.”

Ms. Maier died without any will or other arrangements, or any known heirs. But that simply meant that her estate would be handled by the Illinois laws of intestate succession. And until it was determined how her assets would be distributed, her estate owned her assets — including her copyrights, a form of intangible personal property.

The administrator for the estate, the Cook County Public Administrator, asserted claims against the collectors who had reproduced Maier photos, initially using a state probate court procedure known as a Citation to Discover and/or Recover Assets. The parties negotiated, but reached no agreement.

The estate then filed, in April 2017, a federal copyright infringement suit. The heart of the case is the distinction between the physical photos and negatives, which the defendants own, and the copyright, which the estate claims. The estate is even asserting an unusual claim, of “equitable easement,” which seeks access to the defendant’s physical copies, so that it can use them in registering its copyrights.

In initial skirmishing in the suit, the estate has obtained an initial order preventing the defendants from selling or moving the photos. It is going to be an interesting case — a fight between two owners of different rights in the same photos.

By the way, in case you were wondering about who will eventually own these valuable photo copyrights, the estate administrator reports that a number of people have “unsuccessfully attempted to establish themselves as Maier’s heirs."