An infringement - every patent holder's nightmare. If someone copies something you have a patent on, you can obviously do something about it. Still, it is better to ensure it doesn't come to that. Especially if it involves an infringement under the doctrine of equivalents. In my previous blog I explained how to avoid this type of infringement when you innovate. This time, I am going to explain how to reduce the chances of infringement if you are the patent holder.
Infringement by equivalence: close, but not the same
Let's first take another look at what infringement under the doctrine of equivalents actually means. This is when someone else does not copy your innovation exactly but creates something very similar. It is not identical, but comes so close that it forms a threat to your invention. You can then try to prevent your competitor from marketing the innovation or keeping the innovation on the market. It is just slightly more complicated than it is in the case of a literal infringement when the innovation is literally the same as the claim of your patent.
Proving infringement by equivalence
Equivalence isn't always easy to prove, and the burden of proof is on you. To prove it, the other product must match yours on three points:
-
The function.
-
How that function is performed.
-
The end result.
For example, you have developed a manual orange juicer with a special stainless steel lever to squeeze juice from citrus fruits. You have applied for a patent because the lever does not rust. A competitor markets the juicer with the same lever but made from a synthetic material. Despite the literal difference, this may still be an infringement under the doctrine of equivalents. The function is the same: pressing the orange and preventing the acid from the oranges from causing the lever to rust. The same applies when it comes to how; via a lever made of a non-corrosive material. And the end result is also the same: a glass of fresh juice.
Because it meets all three conditions, the patent holder may well win the case. But only if the claims, the part of the patent that defines what you're protecting, are worded well.
Don't describe every detail
In that clever description of the claims lies the key to limiting equivalence. You do this by using broad wording. Try to write a claim in terms of function and not, for example, claim only screws, when glue can be used to achieve the same function. If you fail to do so you open up the opportunity for innovations to come onto the market that use glue or other bonding agents. A broadly worded description prevents this. For example, in the case of the orange juicer, you could have focused the protection on a non-corrosive material in a broad sense and not just stainless steel.
Claims cannot be amended
It is always better not to push the limits in the wording because you might be able to claim infringement under the doctrine of equivalents anyway. This is because claims cannot be amended at a later stage. For example, if you develop a bicycle with handlebars which can only be mounted with a fixed stem, you can put this in the claims. But if a competitor enters the market with an adjustable handlebar stem, you cannot suddenly claim that you meant to protect that too. You should have worded your claims more broadly from the start.
Tackling infringers
Even if you've done all this, you may still come across a product that looks suspiciously like yours. What then? First, send the other party a letter pointing out your patent. In the bicycle example, you'd explain that while not every detail was copied, you consider the adjustable stem equivalent to the fixed stem you claimed.
If that doesn't work, you can take the matter to court. Just make sure your arguments are strong. Infringement by equivalence is harder to prove than literal infringement because of the three conditions above.
Prevention is better than cure
Infringement by equivalence is frustrating for patent holders, but carefully worded claims prevent a lot of problems. Work with your patent attorney to identify what's essential to your invention, and protect it as broadly as possible.
