Armengaud Guerlain has been at the core of a famous case involving the counterfeiting of a patent for the notices included with prescription and over-the-counter drugs.

In the context of this dispute, the patent was annulled on appeal, though this ruling was later overturned by the French Supreme Court (Cour of Cassation).

The patent in the post-cassation referral process has been limited, and the competitor was convicted of patent infringement.

This is one of the first cases involving the limitation of patent claims during the course of the proceedings.