Surprisingly, the creativity that goes into the design of useful objects, like clothing and furniture, can usually be freely copied because it’s not protected by copyright.

That Balenciaga dress or the crazy lamp made from ostrich feathers and pine cones may be beautiful. But their creative design—no matter how artistic—is not protected by copyright law. This is the main reason there are so many knockoffs in the world of fashion and design.

There’s great debate about whether this fundamental doctrine of intellectual property law is fair. For example, the fashion industry (or at least the segment of the fashion industry that’s more likely to be copied than to copy) has been lobbying Congress for years to pass a bill called the Design Piracy Protection Act, which would extend copyright-ish protection to apparel design. But for the foreseeable future, useful objects can be freely copied.

This raises an obvious question: What counts as a useful object under copyright law? There are going to be close cases, such as a sink (obviously utilitarian) the base of which is essentially a statue of a Balinese dancer (obviously ornate and non-functional). Can that be copied? The answer to that would be very important; someone who wanted to copy the design of a useful article like a sink, or someone who was about to invest in producing original Balinese dancer sinks will wonder whether IKEA could steal their idea.

In a nutshell, a court would try to resolve the question by saying that the artistic elements (the sculptural base) are protected if the elements are in some sense “separate” from the useful aspects of the object. Now that would solve some easy cases like a textile design or graphic on a piece of clothing being protected—simply because those elements are clearly “separate” from the useful aspect of clothing. But the cut of a dress will pretty much never be protected because it is just too intertwined with a garment’s inherent utilitarian function of covering the body

However, there are still much tougher cases and as it turns out, the law isn’t that good at always providing answers.

Consider the rather famous case of a sculpture that turned out to make a terrific bike rack. In this case the court was asked to consider an undulating wire sculpture that was originally created as art, but was eventually quite widely used as a bike rack design. The court decided that if design elements reflect a merger of aesthetic and functional considerations, the artistic aspects of a work cannot be said to be conceptually separable from the utilitarian elements. So far so good.

However, the court then went on to say that “where design elements can be identified as reflecting the designer’s artistic judgment exercised independently of functional influences, conceptual separability exists.” What this means is that you have to look at what the maker intended.

The sculpture was originally a “sculpture” but was marketed as a bike rack. Therefore the court said it wasn’t protected because even though it originally was thought of as a sculpture, the artist came to see it as a bike rack.

While this may sound relatively easy to interpret, the facts are that this area of the law can get even more complicated. Not all courts look at what was in the mind of the artist. They may also look at whether an “ordinary” person would think that the aesthetic or useful aspects would dominate the object.