A Freedom to Operate Primer

The term freedom to operate when applied to patents usually means that the device or process that you plan to design, manufacture, and sell does not infringe any valid patents in force. 

First - a disclaimer. If you are facing a possible patent litigation situation you should get a skilled practitioner with experience in analyzing claims - don't do it yourself.

But engineers and scientists can often do a decent freedom to operate analysis on their own early in the design process by knowing the rather simple rules of patent infringement as well as how to read claims. Below is an admittedly simple but useful primer on how to do that.

First Point

You cannot infringe a patent – you can only infringe a specific claim in a patent. No matter how well a patent specification may describe your device, it is irrelevant if the patent does not accurately claim your device. This is important to know because it means you begin by examining the claims. And usually you will not have to read the complete specification in detail.

Second Point.

Claims are divided into a few independent claims and many dependent claims. They are easy to spot. A dependent claim will always refer to one of the few independent claims and will read something like: “The apparatus of claim 1 wherein the temperature sensor is a thermocouple.” This claim is referring to claim 1 and is therefore dependent on it. This is important because if you can show that you do not infringe the independent claim, then you cannot infringe any of the claims that depend on it.

Third Point.

Here is how to read a claim – any claim. All claims have the structure:

    A preamble.
    A transition phrase.
    A list of elements


1. An active air sampling temperature sensor module, the module comprising: 

    a. a housing mounted interiorly to a cover of an incubator and having a channel therethrough; 
    b. a temperature sensor mounted within the module housing and located within said channel; 
    c. a fan located within said channel for continuously drawing air through said channel, across said sensor, and back into the incubator; and 
    d. a connector for operatively engaging said module to a controller of a heating system of the incubator.

The preamble describes what the invention is:

An active air sampling temperature sensor module

The transition phrase is:

the module comprising:

In patent parlance the word comprising means “including at least”

The list of elements a,b,c,and d.

All patent practitioners are taught to write claims in this way – and the examiners expect claims to be written in this way.

Fourth Point. The All Elements Rule.

To infringe a claim in a patent your device must exhibit each and every element in the claims. Thus in the example above – if you are designing an air sampling temperature sensor module and your module does not have “a fan located within said channel for continuously drawing air through said channel, across said sensor, and back into the incubator” (element c), then you cannot infringe and the analysis is done for that independent claim. If there is only one independent claim in that patent you are through. But be sure to look for other independent claims in the patent before writing it off.

Fifth Point. 
You can only infringe a patent that is in force. A patent expires twenty years after the filing date. Then it is unenforceable. In addition the patent office requires maintenance fees to be paid every four years. These fees escalate each time – in effect encouraging inventors to give up their inventions to the general public. Often inventors decide to not pay the issue fee and the patent expires. If a patent has expired for either reason you have freedom to operate.

Using these key ideas you can fairly quickly eliminate many patents of concern without extensive patent analysis. You might still find one or two that you are concerned about and might then consider consulting a skilled practitioner who has experience in analyzing claims for freedom to operate.


Freedom To Operate Primer
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Mike Ervin
Mike Ervin - Cost Effective Small Business Patent Protection.

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