It’ s a difficult subject to talk about copyright infringement in architecture. Laws on the subject tend to be very vague, and focus on the similarity of appearance of the façades, plans and sections. Slightly more deeply, they look at other facts, such as records of when the design started, was submitted or whether the one who copies had access to the copied design.
At the end of the day aren’t we all subconsciously copying from memory? There is a gray area between copyright infringement and fair use when you take a design as a reference and you change it. However, buildings behave differently in different contexts, geographical locations, orientations and times.
The following case on archdaily is quite interesting, as it describes the approach of a judge, to investigate two almost identical facades, but on one the facade consists of structural elements, yet the other one acts as a curtain wall. More here.
Mitch Tuchman. “What Makes a Copy-Cat a Copy-Cat? The Complex Case of Architectural Copyright” 20 Apr 2014. ArchDaily. Accessed 11 Oct 2015. <http://www.archdaily.com/497568/what-makes-a-copy-cat-a-copy-cat-the-complex-case-of-architectural-copyright/>