Will a competitor be able to get around my patent?

Posted Wednesday, March 30, 2011.

A question I am asked often is, “once I have the patent, will a competitor be able to get around it by copying the invention with just a modest change so that they no longer infringe?”

For example, if I have a patent on a table, and the patent claims recite that the table legs are joined to the surface by nails, can somebody make a table and defeat an infringement claim by joining the legs to the surface with screws?

One proactive way to defeat this would be to change the patent claim to recite that the leg is joined to the surface with a fastener, and then in the specification state that appropriate fasteners may be nails, screws, or other such implements. But after the fact, if we claim nails, can somebody just switch to screws and not be liable for infringement?

Probably not. Since the mid-nineteenth century, the courts have recognized a “Doctrine of Equivalents”. The rationale is that patent law would be very weak if it were so easily defeated, to the extent that inventors would lose their incentive to innovate.

If it is clear to a jury that the alleged infringing design “performs substantially the same function in substantially the same way to obtain the same result,” then it infringes the patent under the Doctrine of Equivalents. In our table example, joining the table leg with a screw most likely meets this test, so even if our patent recited nails and a competitor made their table with screws, they will likely be held liable for infringement even though our patent says nothing about screws.

Who determines whether the substituted design element is substantially the same? This comes back to the Person Having Ordinary Skill In The Art (“PHOSITA”). If a PHOSITA would recognize the substitution as one of just two interchangeable parts, then it is substantially the same. That is why this is a jury question. There will likely be testimony as to what a person skilled in the art would or would not recognize as being interchangeable, and a jury makes the credibility determination as to which side’s assertion about what a PHOSITA would know is more likely.

The Doctrine of Equivalents helps assure strong patent rights, by ensuring a competitor can’t pirate a patented invention by making some insignificant change that gets the device legally outside of what is literally claimed, while retaining the essence of the patented invention. In most instances a competitor won’t be able to get around your patent because a court would invoke the Doctrine of Equivalents to find infringement.

Litigation is expensive, however, so the best solution is to employ a skilled patent drafter with the skills to protect your invention such that it is difficult for a copier to find an insignificant change to make that isn’t already covered by the patent.

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