An expressive interface is a user interface element whose specific creative presentation may be protected by copyright. This can include original visual or textual choices—such as artwork, icons, or distinctive screen layouts—rather than the underlying idea or function the interface communicates.
In software reimplementation, reproducing a feature’s behavior is different from copying its expressive presentation. A developer may create a compatible function using original design, while reproducing distinctive interface details can raise copyright concerns. Security teams evaluating alternative software should also test it safely: visual similarity or compatibility does not establish how it was built or whether it handles data securely.