Why did the Canfield Joint Patent Expire Early? Patent Office Fees

US patent #5,699,695 issued on December 23, 1997 and could have been in force until May 2016. Instead, the “robotic carpal wrist” structure, better known as the Canfield Joint, the patent disclosed entered the public domain on December 26, 2001! Like everything else in the public domain, the public is free to make, use, and sell their own versions or copies of the Canfield Joint. So what happened, why didn’t Professor Canfield get the full twenty year patent term?

In general, a patent gives the holder certain rights to exclude others utilizing the invention described in the patent for a limited term. In the United States, this term is up to twenty years from the filing date of the patent. Applications filed before June 8, 1995 were actually entitled to a seventeen year patent term from the date the patent issued, which led to the interesting, nefarious world of “submarine patents” but that, as they say, is another story!

As emphasized above, patents are good for up to twenty years, but your mileage may vary. After a patent issues, the inventor or the owner of the patent must pay a maintenance fee to the patent office in order to keep the associated patent rights in force. In order to defray the costs of examining and issuing patents, the patent office also charges application and issue fees. These fees are due according to the following schedule:



(large entity/small entity)

Due Date

Application Fee $1,250/$625 Upon initial filing of patent application.
Issue Fee $1,740/$870 When the patent issues (i.e. the patent office approves the patent application). Current average time from application to issuance: 34 months.
First Maintenance Fee $1,130/$565 3.5 years after the patent issues.
Second Maintenance Fee $2,850/$1,425 7.5 years after the patent issues.
Third Maintenance Fee $4,730/$2,365 11.5 years after the patent issues.

If maintenance fees are not paid, the patent expires early and the associated technology enters the public domain. The maintenance fee requirement serves at least two functions: it helps spread the cost of obtaining a patent out over a longer period and it provides a mechanism to introduce a patented technology into the public domain early.

Securing a patent is a reasonably costly and time intensive process from the patent office’s prospective as well as the inventor’s prospective. A patent examiner may spend nearly as much time reviewing a patent application as was put into writing the application initially, but the initial patent application fee of $1,250 ($625 for most individual inventors, companies with less than 500 employees, and non-profits. These groups are known as “small entities”) does not fully cover this cost. Issue and maintenance fees help to offset the patent office’s administrative costs of examining and issuing a patent. Currently, application, issue, and maintenance fees sum to $11,700 ($5,850 for small entities), with the vast majority of the monies due well into the life of the patent when the patent owner has either established a lucrative business around the patented technology, or has lost interest in the technology.

The maintenance fee requirement provides an automatic mechanism to introduce patented technology into the public domain early via economics. If a patent issues, but the patent owner never integrates the technology into a product, products based on the invention fail commercially, or the patent owner otherwise fails to make money off of the invention, the patent owner has little motivation to pay a fee to maintain their rights in the invention. In this familiar scenario, the patent owner does not pay a maintenance fee and the underutilized or abandoned technology is put into the public domain early, for others to play with.

This is exactly what happened with the Canfield Joint patent. The owner of the patent, Virginia Tech Intellectual Properties, Inc., failed to pay the first maintenance fee, therefore the patented technology disclosed in the ‘695 patent entered the public domain more than a decade before it would have been freely available, had the patent owners paid all their maintenance fees!

Patents expire from failure to pay maintenance fees every week. The patent office releases a list of recently expired patents in it Official Gazette. Patent professionals can also assist you in determining if an interesting patent is in danger of expiring early and what that means in terms of your ability to use the patented technology.

Happy creating!