Assignment
Patent assignments must be recorded in writing (L613-8 IPC).
Licenses
It is possible to grant licenses for a patent.
If such licenses include resolutory clauses in the event of the licensee’s failure to meet obligations (e.g., semi-annual sales volume reports, conclusion of sub-licenses, etc.), the proprietor must act promptly in case of breach. Indeed, if the proprietor does not react for many years, it will be considered that they accept this state of affairs, especially if they have played an active role in the licensee’s company (Paris Court of Appeal, Pole 5, 1st ch., May 7, 2014).
Recordals
Recordals made in the National Register of Patents (RNB) allow courts to presume ownership of rights, and it is not necessary to request additional documents (Paris Court of Appeal, Pole 1, 3rd ch., January 28, 2014).
While assignments and the establishment of rights must be recorded in writing under penalty of nullity (L613-8 IPC), their intrinsic validity (e.g., lack of signature, defects in consent, etc.) can only be challenged by the parties (i.e., relative nullity, Paris Court of Appeal, Pole 1, 3rd ch., January 28, 2014). In particular, the acts may well escape French law if the parties are foreign or have so decided (Paris Court of Appeal, Pole 1, 3rd ch., January 28, 2014).
For a patent to be enforceable against third parties, any assignment must be recorded in the register (L613-9 IPC) (French Supreme Court, com. ch., Case No. 22-22.999, April 24, 2024). However, a rectification during proceedings can remedy this unenforceability, including for infringement acts prior to the recordal (Article 126 of the French Code of Civil Procedure).