What To Do When Patent Is Potentially Invalid?
Sometimes, one becomes aware of a patent that may be invalid. As an example, there is presently an online uproar about U.S. Patent No. 7,028,023, which is directed to a type of linked list. Linked lists are data structures that computer programmers commonly employ to store information that needs to be accessed sequentially.
Claim 1 of this patent recites:
1. A computerized list that may be traversed in at least two sequences comprising:
- a plurality of items that are contained in said computerized list; and
- a primary pointer and an auxiliary pointer for each of said items of said computerized list such that each of said items has an associated primary pointer and an associated auxiliary pointer, said primary pointer functioning as a primary linked list to direct a computer program to a first following item and defining a first sequence to traverse said computerized list, said auxiliary pointer functioning as an auxiliary linked list to direct said computer program to a second following item and defining a second sequence to traverse said computerized list.
Some people in the online community believe that this patent could be invalid in view of various prior art, including "skip lists." (As a coincidence - one of my assignments during my undergraduate education at the University of Toronto was to implement skip lists -- before an article explaining the data structure first published in 1990 -- as a favor to the author.)
Assuming that these people are correct and the patent is invalid, what should you do?
- If the patent has not been asserted against you, then you may choose to implement the claimed technology assuming that you can invalidate the patent later.
- If the patent is (e.g., later) asserted, you may
- request the U.S. Patent & Trademark Office to reexamine the patent based on the prior art;
- use the prior art to invalidate the patent during trial; or
- notify the patent owner that you have prior art that could invalidate their patent.
Each approach has advantages and disadvantages. As examples, the reexamination may invalidate the claims, but may result in narrower claims that are valid and that you may still infringe; the court may be convinced by the patent owner that the prior art does not invalidate the claims; or by identifying the prior art, you may give the patent owner a head start in claim construction arguments to use during trial.
As is usual, which of the many options you choose will depend on the facts of the case.
