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How to avoid infringement under the doctrine of equivalents on your patent

EP&C Blog Equivalente inbreukAn 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 under the doctrine of equivalents: not exactly 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.

Demonstrating infringement under the doctrine of equivalents

What complicates matters is that equivalence is not always easy to prove and the burden of proof is on you if you want to take on an infringer. On top of that, to prove infringement under the doctrine of equivalents, the infringer's innovation must be the same when it comes to the following:
•    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.

The invention is not exactly the same because of the different materials used. However it does come close because it meets the three conditions mentioned above. Therefore, the patent holder may actually be proven right when it comes to the infringement. However that is only possible if the claims - that which you are protecting - are cleverly described.

You should not describe everything down to the tiniest 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. Then you should have worded your claims more broadly.

Tackling infringers

You may actually already have done exactly what I’ve described here but nevertheless still end up coming across an innovation that looks suspiciously like yours. What do you do then? First, send the potential infringer a letter to make them aware of your patent. To use the example of the bicycle, let them know that you can see that not all the details have been copied exactly, but that as far as you are concerned the adjustable stem is equivalent to the fixed stem you claimed.

If this does not work, you can try taking the matter to court. Just make sure you have sufficient arguments. Infringement under the doctrine of equivalents is simply harder to prove than a literal infringement because of the conditions the innovation has to meet.

Prevention is better than cure

Infringement under the doctrine of equivalents is annoying for patent holders but by carefully wording the patent claims you can avoid a lot of problems. Together with your patent attorney think carefully about what is essential to your invention and protect it as broadly as possible. After all, prevention is better than cure!