Quote from Martin Schweiger on August 7, 2021, 11:43 am

These are some drawbacks that I have noticed over the years:

• some countries publish basic data of patent applications before they are published after 18 months. For example in Singapore, a patent application will be visible in the patent register with its title and applicant name. Once this patent application is deemed to be withdrawn by not paying the filing fee, this will also be visible, despite the Paris Convention priority of this application still being valid. The Faint of Heart cannot easily bear with that. And people with half-knowledge about patent law will think that this constitutes a flaw in the patent portfolio, while it is not. If you show your patent portfolio to someone, such as an investor, you could highlight this with a remark as follows: "All is in good order here. Referring to columns I and J in the excel list, there were 16 patent applications marked as “2. Provisional filings” + “Disclosure taken up into xxx”. These patent applications were part of a bigger filing campaign, and they could be abandoned because their disclosure was taken up into later PCT patent applications, claiming their earlier Paris Convention priorities. This provides a full protection for the innovation made, combined with optimized costs for better use of the company resources."
• combining a multitude of inventions of different inventors can lead to more administrative effort required if these inventors have claims for remuneration out of a use of their inventions. This is mostly an issue in Germany because of an "Employees' Invention Remuneration Act" being in place.
• combining a multitude of inventions of different inventors can lead to more administrative effort required if these patent applications are later licensed out to third parties. The license agreement should specify which invention is licensed and which one is not. Otherwise the patent owner can get into something that we call "Ethicon-Situation": In 1989, Ethicon, a manufacturer of surgical instruments, filed a patent infringement suit against a competitor, United States Surgical, over U.S. Patent No. 4,535,773. The inventor named on the patent was Dr. Inbae Yoon. Yoon granted Ethicon an exclusive license to practice his invention. The patent had 55 claims but only two claims were asserted against U.S. Surgical: claims 34 and 50. During the lawsuit, U.S. Surgical learned of a co-inventor named Young Jae Choi. Choi was an electronics technician who collaborated with Dr. Yoon for 18 months. US Surgical asked the court to add Choi as an inventor. The court agreed finding that Choi had co-invented claims 33 and 47. Two claims that were not even involved in the lawsuit. The court found that there was corroborating evidence that supported Choi’s assertions that he was an inventor. The evidence was dated notes and drawings that Choi had along with his technical abilities as an electronics technician. The court dismissed Ethicon’s lawsuit because Choi had granted U.S. Surgical a retroactive license to the patent.
• combining a multitude of inventions  "ABCD" into one single PCT patent application, and later prosecuting them to grant, using divisional/continuation patent applications will lead to a patent family of a multitude of patents that are linked over their claim priorities. In countries that have a "file history estoppel" doctrine in place, this can mean that all file history estoppels in that patent family apply to all members of that patent family. Prosecutors and litigators need to have that in mind.
• combining a multitude of inventions  "ABCD" into one single PCT patent application, and later prosecuting them to grant, using divisional/continuation patent applications and even divisional/continuation patent applications from earlier divisional/continuation patent applications can be difficult in some countries, such as CN and BR. You need to tell the patent attorney who prosecutes these national patent applications in advance that there will be such situations arising in the future.

Taken all drawbacks together, one must be careful and knowledgeable if the 4x4 Patent Filing strategy is chosen. Good patent attorneys are careful and knowledgeable, so there is no real problem here.